diff --git a/Makefile b/Makefile new file mode 100644 index 0000000..c594100 --- /dev/null +++ b/Makefile @@ -0,0 +1,14 @@ +data/corpus-simple-50.json: extract-fields.ini data/corpus_WoS_vol1-50.json + npx ezs -e extract-fields.ini + +data/corpus-simple-rnsr-50.json: enrich-rnsr.ini data/corpus-simple-50.json + npx ezs -e enrich-rnsr.ini + +data/corpus-simple-etab-50.json: enrich-etab.ini data/corpus-simple-rnsr-50.json + npx ezs -e enrich-etab.ini + +data/corpus-simple-instituts-50.json: enrich-institutes.ini data/corpus-simple-etab-50.json + npx ezs -e enrich-institutes.ini + +data/corpus-simple-teeft-en-50.json: enrich-teeft-en.ini data/corpus-simple-instituts-50.json + npx ezs -e enrich-teeft-en.ini diff --git a/data/corpus-simple-50.json b/data/corpus-simple-50.json index 316642e..1dd92d9 100644 --- a/data/corpus-simple-50.json +++ b/data/corpus-simple-50.json @@ -862,7 +862,7 @@ { "uri": "WOS:000332995300006", "title": "Arctic sea ice and atmospheric circulation under the GeoMIP G1 scenario", - "abstract": "We analyze simulated sea ice changes in eight different Earth System Models that have conducted experiment G1 of the Geoengineering Model Intercomparison Project (GeoMIP). The simulated response of balancing abrupt quadrupling of CO2 (abrupt4xCO2) with reduced shortwave radiation successfully moderates annually averaged Arctic temperature rise to about 1 degrees C, with modest changes in seasonal sea ice cycle compared with the preindustrial control simulations (piControl). Changes in summer and autumn sea ice extent are spatially correlated with temperature patterns but much less in winter and spring seasons. However, there are changes of 20% in sea ice concentration in all seasons, and these will induce changes in atmospheric circulation patterns. In summer and autumn, the models consistently simulate less sea ice relative to preindustrial simulations in the Beaufort, Chukchi, East Siberian, and Laptev Seas, and some models show increased sea ice in the Barents/Kara Seas region. Sea ice extent increases in the Greenland Sea, particularly in winter and spring and is to some extent associated with changed sea ice drift. Decreased sea ice cover in winter and spring in the Barents Sea is associated with increased cyclonic activity entering this area under G1. In comparison, the abrupt4xCO2 experiment shows almost total sea ice loss in September and strong correlation with regional temperatures in all seasons consistent with open ocean conditions. The tropospheric circulation displays a Pacific North America pattern-like anomaly with negative phase in G1-piControl and positive phase under abrupt4xCO2-piControl. ; Key Points ; Analysis of eight ESM focused on Arctic sea ice and feedback Response of Arctic to G1 geoengineering shows clear regional differences Sea ice is far different in detail under G1 than in pre industrial", + "abstract": "We analyze simulated sea ice changes in eight different Earth System Models that have conducted experiment G1 of the Geoengineering Model Intercomparison Project (GeoMIP). The simulated response of balancing abrupt quadrupling of CO2 (abrupt4xCO2) with reduced shortwave radiation successfully moderates annually averaged Arctic temperature rise to about 1 degrees C, with modest changes in seasonal sea ice cycle compared with the preindustrial control simulations (piControl). Changes in summer and autumn sea ice extent are spatially correlated with temperature patterns but much less in winter and spring seasons. However, there are changes of 20% in sea ice concentration in all seasons, and these will induce changes in atmospheric circulation patterns. In summer and autumn, the models consistently simulate less sea ice relative to preindustrial simulations in the Beaufort, Chukchi, East Siberian, and Laptev Seas, and some models show increased sea ice in the Barents/Kara Seas region. Sea ice extent increases in the Greenland Sea, particularly in winter and spring and is to some extent associated with changed sea ice drift. Decreased sea ice cover in winter and spring in the Barents Sea is associated with increased cyclonic activity entering this area under G1. In comparison, the abrupt4xCO2 experiment shows almost total sea ice loss in September and strong correlation with regional temperatures in all seasons consistent with open ocean conditions. The tropospheric circulation displays a Pacific North America pattern-like anomaly with negative phase in G1-piControl and positive phase under abrupt4xCO2-piControl. ; ; Analysis of eight ESM focused on Arctic sea ice and feedback Response of Arctic to G1 geoengineering shows clear regional differences Sea ice is far different in detail under G1 than in pre industrial", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -913,7 +913,7 @@ { "uri": "WOS:000334264900040", "title": "Impact of the Atlanticmeridional overturning circulation on ocean heat storage and transient climate change", - "abstract": "We propose here that the Atlantic meridional overturning circulation (AMOC) plays an important role in setting the effective heat capacity of the World Ocean and thus impacts the pace of transient climate change. The depth and strength of AMOC are shown to be strongly correlated with the depth of heat storage across a suite of state-of-the-art general circulation models (GCMs). In those models with a deeper and stronger AMOC, a smaller portion of the heat anomaly remains in the ocean mixed layer, and consequently, the surface temperature response is delayed. Representations of AMOC differ vastly across the GCMs, providing a major source of intermodel spread in the sea surface temperature (SST) response. A two-layer model fit to the GCMs is used to demonstrate that the intermodel spread in SSTs due to variations in the ocean's effective heat capacity is significant but smaller than the spread due to climate feedbacks. ; Key Points AMOC plays a key role in setting the effective heat capacity of the World Ocean AMOC properties are correlated with depth of heat storage across CMIP5 GCMs Ocean heat storage is a major source of inter-GCM variability in SST response", + "abstract": "We propose here that the Atlantic meridional overturning circulation (AMOC) plays an important role in setting the effective heat capacity of the World Ocean and thus impacts the pace of transient climate change. The depth and strength of AMOC are shown to be strongly correlated with the depth of heat storage across a suite of state-of-the-art general circulation models (GCMs). In those models with a deeper and stronger AMOC, a smaller portion of the heat anomaly remains in the ocean mixed layer, and consequently, the surface temperature response is delayed. Representations of AMOC differ vastly across the GCMs, providing a major source of intermodel spread in the sea surface temperature (SST) response. A two-layer model fit to the GCMs is used to demonstrate that the intermodel spread in SSTs due to variations in the ocean's effective heat capacity is significant but smaller than the spread due to climate feedbacks. ; AMOC plays a key role in setting the effective heat capacity of the World Ocean AMOC properties are correlated with depth of heat storage across CMIP5 GCMs Ocean heat storage is a major source of inter-GCM variability in SST response", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -940,7 +940,7 @@ { "uri": "WOS:000334264900041", "title": "Astronomically forced variations in western African rainfall ( 21 N-20 S) during the Last Interglacial period", - "abstract": "This study documents the long-term evolution of western African precipitation during the Last Interglacial (LIG). We compare geochemical records obtained on nine sediment cores from the western African margin to a transient simulation (130-115ka) performed with an ocean-atmosphere general circulation model and insolation as sole forcing. Good agreement between proxy records and model outputs indicates that long-term changes in western African precipitation largely responded to insolation variations during most of the LIG. After an early LIG dry phase (related to high-latitude iceberg melting or dating uncertainties), boreal summer insolation controlled the intensification of the North African monsoon between 127 and 122ka, perhaps facilitating human migrations out of Africa. Equatorial African rainfall slightly increased throughout the LIG in response to increasing annual insolation. East-west contrasting rainfall evolutions at 10-20 degrees S illustrate the complex southern African response, in contrast to more direct responses of North and equatorial western Africa, to insolation forcing. ; Key Points ; Insolation controls changes in western African rainfall during most of the LIG Early LIG meltwater may have delayed the North African monsoon intensification Complex response of southern African rainfall with east-west contrasting trends", + "abstract": "This study documents the long-term evolution of western African precipitation during the Last Interglacial (LIG). We compare geochemical records obtained on nine sediment cores from the western African margin to a transient simulation (130-115ka) performed with an ocean-atmosphere general circulation model and insolation as sole forcing. Good agreement between proxy records and model outputs indicates that long-term changes in western African precipitation largely responded to insolation variations during most of the LIG. After an early LIG dry phase (related to high-latitude iceberg melting or dating uncertainties), boreal summer insolation controlled the intensification of the North African monsoon between 127 and 122ka, perhaps facilitating human migrations out of Africa. Equatorial African rainfall slightly increased throughout the LIG in response to increasing annual insolation. East-west contrasting rainfall evolutions at 10-20 degrees S illustrate the complex southern African response, in contrast to more direct responses of North and equatorial western Africa, to insolation forcing. ; ; Insolation controls changes in western African rainfall during most of the LIG Early LIG meltwater may have delayed the North African monsoon intensification Complex response of southern African rainfall with east-west contrasting trends", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1017,7 +1017,7 @@ { "uri": "WOS:000333578800056", "title": "Predictability of the quasi-biennial oscillation and its northern winter teleconnection on seasonal to decadal timescales", - "abstract": "The predictability of the quasi-biennial oscillation (QBO) is examined in initialized climate forecasts extending out to lead times of years. We use initialized retrospective predictions made with coupled ocean-atmosphere climate models that have an internally generated QBO. We demonstrate predictability of the QBO extending more than 3 years into the future, well beyond timescales normally associated with internal atmospheric processes. Correlation scores with observational analyses exceed 0.7 at a lead time of 12months. We also examine the variation of predictability with season and QBO phase and find that skill is lowest in winter. An assessment of perfect predictability suggests that higher skill may be achievable through improved initialization and climate modeling of the QBO, although this may depend on the realism of gravity wave source parameterizations in the models. Finally, we show that skilful prediction of the QBO itself does not guarantee predictability of the extratropical winter teleconnection that is important for surface winter climate prediction. ; Key Points ; The QBO is skilfully predicted in seasonal-decadal forecast systems Further improvements in predictions of the QBO are possible The QBO winter surface teleconnection is reproduced with mixed success", + "abstract": "The predictability of the quasi-biennial oscillation (QBO) is examined in initialized climate forecasts extending out to lead times of years. We use initialized retrospective predictions made with coupled ocean-atmosphere climate models that have an internally generated QBO. We demonstrate predictability of the QBO extending more than 3 years into the future, well beyond timescales normally associated with internal atmospheric processes. Correlation scores with observational analyses exceed 0.7 at a lead time of 12months. We also examine the variation of predictability with season and QBO phase and find that skill is lowest in winter. An assessment of perfect predictability suggests that higher skill may be achievable through improved initialization and climate modeling of the QBO, although this may depend on the realism of gravity wave source parameterizations in the models. Finally, we show that skilful prediction of the QBO itself does not guarantee predictability of the extratropical winter teleconnection that is important for surface winter climate prediction. ; ; The QBO is skilfully predicted in seasonal-decadal forecast systems Further improvements in predictions of the QBO are possible The QBO winter surface teleconnection is reproduced with mixed success", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1056,7 +1056,7 @@ { "uri": "WOS:000333578800054", "title": "Modifications of the quasi-biennial oscillation by a geoengineering perturbation of the stratospheric aerosol layer", - "abstract": "This paper examines the impact of geoengineering via stratospheric sulfate aerosol on the quasi-biennial oscillation (QBO) using the NASA Goddard Earth Observing System version 5 Chemistry Climate Model. We performed four 30 year simulations with a continuous injection of sulfur dioxide on the equator at 0 degrees longitude. The four simulations differ by the amount of sulfur dioxide injected (5 Tg/yr and 2.5 Tg/yr) and the altitude of the injection (16km-25km and 22km-25km). We find that such an injection dramatically alters the quasi-biennial oscillation, prolonging the phase of easterly shear with respect to the control simulation. This is caused by the increased aerosol heating and associated warming in the tropical lower stratosphere and higher residual vertical velocity. In the case of maximum perturbation, i.e., highest stratospheric aerosol burden, the lower tropical stratosphere is locked into a permanent westerly QBO phase. ; Key Points ; Geoengineering aerosol would prolong the westerly phase of the QBO Large geoengineering stratospheric aerosol injections might interrupt the QBO QBO changes are due to aerosol warming and increased residual vertical velocity", + "abstract": "This paper examines the impact of geoengineering via stratospheric sulfate aerosol on the quasi-biennial oscillation (QBO) using the NASA Goddard Earth Observing System version 5 Chemistry Climate Model. We performed four 30 year simulations with a continuous injection of sulfur dioxide on the equator at 0 degrees longitude. The four simulations differ by the amount of sulfur dioxide injected (5 Tg/yr and 2.5 Tg/yr) and the altitude of the injection (16km-25km and 22km-25km). We find that such an injection dramatically alters the quasi-biennial oscillation, prolonging the phase of easterly shear with respect to the control simulation. This is caused by the increased aerosol heating and associated warming in the tropical lower stratosphere and higher residual vertical velocity. In the case of maximum perturbation, i.e., highest stratospheric aerosol burden, the lower tropical stratosphere is locked into a permanent westerly QBO phase. ; ; Geoengineering aerosol would prolong the westerly phase of the QBO Large geoengineering stratospheric aerosol injections might interrupt the QBO QBO changes are due to aerosol warming and increased residual vertical velocity", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1089,7 +1089,7 @@ { "uri": "WOS:000333578800044", "title": "The implication of radiative forcing and feedback for meridional energy transport", - "abstract": "The distributions of radiative forcing and feedback in the Coupled Model Intercomparison Project phase 5 abrupt4xCO2 and Historical experiments are diagnosed, with a focus on their effects on the zonal mean structure of the top-of-the-atmosphere radiation anomalies and implications for the meridional energy transport. It is found that because the greenhouse gas longwave forcing peaks in the low latitudes, it reinforces the equator-to-pole net radiation gradient and accounts for the increase in the poleward energy transport in both hemispheres under global warming. The shortwave forcing by aerosol, ozone, etc. peaks in the Northern Hemisphere and instead implies an interhemispheric energy transport. Although the water vapor feedback also reinforces the equator-to-pole gradient of the net radiation, the temperature and albedo feedback act against it. The feedback tend to offset the zonal mean radiation anomaly caused by the forcing, although the overall feedback effect on the energy transport is rather uncertain, mainly due to the uncertainty in the cloud feedback. ; Key Points ; CO2 forcing increases meridional gradient in net radiation Forcing, rather than feedback, accounts for enhanced poleward energy transport Aerosol forcing accounts for an inter-hemispheric transport anomaly", + "abstract": "The distributions of radiative forcing and feedback in the Coupled Model Intercomparison Project phase 5 abrupt4xCO2 and Historical experiments are diagnosed, with a focus on their effects on the zonal mean structure of the top-of-the-atmosphere radiation anomalies and implications for the meridional energy transport. It is found that because the greenhouse gas longwave forcing peaks in the low latitudes, it reinforces the equator-to-pole net radiation gradient and accounts for the increase in the poleward energy transport in both hemispheres under global warming. The shortwave forcing by aerosol, ozone, etc. peaks in the Northern Hemisphere and instead implies an interhemispheric energy transport. Although the water vapor feedback also reinforces the equator-to-pole gradient of the net radiation, the temperature and albedo feedback act against it. The feedback tend to offset the zonal mean radiation anomaly caused by the forcing, although the overall feedback effect on the energy transport is rather uncertain, mainly due to the uncertainty in the cloud feedback. ; ; CO2 forcing increases meridional gradient in net radiation Forcing, rather than feedback, accounts for enhanced poleward energy transport Aerosol forcing accounts for an inter-hemispheric transport anomaly", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1119,7 +1119,7 @@ { "uri": "WOS:000332995300011", "title": "Evaluation of interpolation techniques for the creation of gridded daily precipitation ( 1 x 1 km2); Cyprus, 1980-2010", - "abstract": "High-resolution gridded daily data sets are essential for natural resource management and the analyses of climate changes and their effects. This study aims to evaluate the performance of 15 simple or complex interpolation techniques in reproducing daily precipitation at a resolution of 1km(2) over topographically complex areas. Methods are tested considering two different sets of observation densities and different rainfall amounts. We used rainfall data that were recorded at 74 and 145 observational stations, respectively, spread over the 5760km(2) of the Republic of Cyprus, in the Eastern Mediterranean. Regression analyses utilizing geographical copredictors and neighboring interpolation techniques were evaluated both in isolation and combined. Linear multiple regression (LMR) and geographically weighted regression methods (GWR) were tested. These included a step-wise selection of covariables, as well as inverse distance weighting (IDW), kriging, and 3D-thin plate splines (TPS). The relative rank of the different techniques changes with different station density and rainfall amounts. Our results indicate that TPS performs well for low station density and large-scale events and also when coupled with regression models. It performs poorly for high station density. The opposite is observed when using IDW. Simple IDW performs best for local events, while a combination of step-wise GWR and IDW proves to be the best method for large-scale events and high station density. This study indicates that the use of step-wise regression with a variable set of geographic parameters can improve the interpolation of large-scale events because it facilitates the representation of local climate dynamics. ; Key Points ; Interpolation of daily rainfall data using 15 spatial interpolation methods Relative skill of interpolation techniques depends on observation density High and low rainfall events should be treated with different techniques", + "abstract": "High-resolution gridded daily data sets are essential for natural resource management and the analyses of climate changes and their effects. This study aims to evaluate the performance of 15 simple or complex interpolation techniques in reproducing daily precipitation at a resolution of 1km(2) over topographically complex areas. Methods are tested considering two different sets of observation densities and different rainfall amounts. We used rainfall data that were recorded at 74 and 145 observational stations, respectively, spread over the 5760km(2) of the Republic of Cyprus, in the Eastern Mediterranean. Regression analyses utilizing geographical copredictors and neighboring interpolation techniques were evaluated both in isolation and combined. Linear multiple regression (LMR) and geographically weighted regression methods (GWR) were tested. These included a step-wise selection of covariables, as well as inverse distance weighting (IDW), kriging, and 3D-thin plate splines (TPS). The relative rank of the different techniques changes with different station density and rainfall amounts. Our results indicate that TPS performs well for low station density and large-scale events and also when coupled with regression models. It performs poorly for high station density. The opposite is observed when using IDW. Simple IDW performs best for local events, while a combination of step-wise GWR and IDW proves to be the best method for large-scale events and high station density. This study indicates that the use of step-wise regression with a variable set of geographic parameters can improve the interpolation of large-scale events because it facilitates the representation of local climate dynamics. ; ; Interpolation of daily rainfall data using 15 spatial interpolation methods Relative skill of interpolation techniques depends on observation density High and low rainfall events should be treated with different techniques", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -1197,7 +1197,7 @@ { "uri": "WOS:000333885700023", "title": "Cirrus cloud susceptibility to the injection of ice nuclei in the upper troposphere", - "abstract": "Due to their net warming effect, cirrus clouds play a crucial role in the climate system. A recently proposed climate engineering mechanism (CEM) intends to reduce high cloud cover by seeding cirrus clouds with efficient ice nuclei (IN) and therefore cool climate. Here, the susceptibility of cirrus clouds to the injection of ice nuclei in the upper troposphere is investigated in the extended Community Atmospheric Model version 5 (CAM5). Due to large uncertainties associated with the dominant ice nucleation mechanism in cirrus clouds, different control cases were simulated. In addition to pure homogeneous and heterogeneous nucleation, cases with competition between homogeneous and heterogeneous nucleation and different fractions of mineral dust active as IN were considered. Whereas seeding in the pure heterogeneous case leads to a strong warming due to overseeding, an optimal seeding IN concentration of approximately 18 l(-1) was found for the other cases. For the optimal seeding concentration, a reduction in the net cloud forcing (NCF) of up to 2 W m(-2) was simulated, corresponding to a strong cooling effect. To optimize the cooling and minimize the amount of seeding material, globally nonuniform seeding strategies were tested, with minimal seeding in the summer hemisphere and in the tropics. With seeding applied to less than half the globe, an even stronger reduction in the NCF was achieved. This suggests that the CEM could work for an atmosphere even with considerable heterogeneous ice nucleation and that the desired cooling could be obtained without seeding the entire globe. ; Key Points Cirrus cloud seeding in the upper troposphere was simulated in CAM5 Both cirrus cloud susceptibility and short-term climate response were analyzed Even globally non-uniform injection of IN leads to the desired cooling", + "abstract": "Due to their net warming effect, cirrus clouds play a crucial role in the climate system. A recently proposed climate engineering mechanism (CEM) intends to reduce high cloud cover by seeding cirrus clouds with efficient ice nuclei (IN) and therefore cool climate. Here, the susceptibility of cirrus clouds to the injection of ice nuclei in the upper troposphere is investigated in the extended Community Atmospheric Model version 5 (CAM5). Due to large uncertainties associated with the dominant ice nucleation mechanism in cirrus clouds, different control cases were simulated. In addition to pure homogeneous and heterogeneous nucleation, cases with competition between homogeneous and heterogeneous nucleation and different fractions of mineral dust active as IN were considered. Whereas seeding in the pure heterogeneous case leads to a strong warming due to overseeding, an optimal seeding IN concentration of approximately 18 l(-1) was found for the other cases. For the optimal seeding concentration, a reduction in the net cloud forcing (NCF) of up to 2 W m(-2) was simulated, corresponding to a strong cooling effect. To optimize the cooling and minimize the amount of seeding material, globally nonuniform seeding strategies were tested, with minimal seeding in the summer hemisphere and in the tropics. With seeding applied to less than half the globe, an even stronger reduction in the NCF was achieved. This suggests that the CEM could work for an atmosphere even with considerable heterogeneous ice nucleation and that the desired cooling could be obtained without seeding the entire globe. ; Cirrus cloud seeding in the upper troposphere was simulated in CAM5 Both cirrus cloud susceptibility and short-term climate response were analyzed Even globally non-uniform injection of IN leads to the desired cooling", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -1232,7 +1232,7 @@ { "uri": "WOS:000333885700020", "title": "What controls the interannual variation of the wet season onsets over the Amazon?", - "abstract": "Previous studies have established that sea surface temperature anomalies (SSTAs) in the tropical Pacific and Atlantic are the main forcing of the interannual variation of the wet season onsets in the Amazon. However, this variation appears to be complex and not uniquely determined by SSTAs. What causes such a complexity and to what extent the interannual variation of the wet season onsets is predictable remain unclear. This study suggests that such a complex relationship is the result of several competing processes, which are nonlinearly related to the SSTAs. In particular, three dry season conditions are crucial for determining interannual variation of the wet season onset. (i) A poleward shift of the Southern Hemisphere subtropical jet (SHSJ) over the South American sector, initiated from a wave train-like structure possibly forced by south central Pacific SST patterns, can prevent cold frontal systems from moving northward into the Amazon. This delays cold air incursion and results in late wet season onset over the southern Amazon. (ii) An anomalous anticyclonic center, which enhances westerly wind at 850hPa over the southern Amazon and also the South American low-level jets, leads to moisture export from the southern Amazon to La Plata basin and reduces convective systems that provide elevated diabatic heating. (iii) Smaller convective available potential energy (CAPE) limits local thermodynamically driven convection. Based on the stepwise and partial least squares regressions, these three selected preseasonal conditions (Nino 4, SHSJ, and CAPE) can explain 57% of the total variance of the wet season onset. ; Key Points ; The wet season onset over the Amazon is not uniquely deterimined by SSTAs A poleward SHSJ, enhanced U850, and lower CAPE are crucial for delayed onset Selected conditions can explain 57% of the total variance", + "abstract": "Previous studies have established that sea surface temperature anomalies (SSTAs) in the tropical Pacific and Atlantic are the main forcing of the interannual variation of the wet season onsets in the Amazon. However, this variation appears to be complex and not uniquely determined by SSTAs. What causes such a complexity and to what extent the interannual variation of the wet season onsets is predictable remain unclear. This study suggests that such a complex relationship is the result of several competing processes, which are nonlinearly related to the SSTAs. In particular, three dry season conditions are crucial for determining interannual variation of the wet season onset. (i) A poleward shift of the Southern Hemisphere subtropical jet (SHSJ) over the South American sector, initiated from a wave train-like structure possibly forced by south central Pacific SST patterns, can prevent cold frontal systems from moving northward into the Amazon. This delays cold air incursion and results in late wet season onset over the southern Amazon. (ii) An anomalous anticyclonic center, which enhances westerly wind at 850hPa over the southern Amazon and also the South American low-level jets, leads to moisture export from the southern Amazon to La Plata basin and reduces convective systems that provide elevated diabatic heating. (iii) Smaller convective available potential energy (CAPE) limits local thermodynamically driven convection. Based on the stepwise and partial least squares regressions, these three selected preseasonal conditions (Nino 4, SHSJ, and CAPE) can explain 57% of the total variance of the wet season onset. ; ; The wet season onset over the Amazon is not uniquely deterimined by SSTAs A poleward SHSJ, enhanced U850, and lower CAPE are crucial for delayed onset Selected conditions can explain 57% of the total variance", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -1385,7 +1385,7 @@ { "uri": "WOS:000332991000059", "title": "Surface warming patterns drive tropical rainfall pattern responses to CO2 forcing on all timescales", - "abstract": "Mechanisms behind regional tropical rainfall responses to CO2 forcing are examined in idealized climate model experiments, traceable to transient forcing scenarios. As previously shown, the pattern of the first-year response of dynamical precipitation change to an abrupt CO2 increase is similar to the century-scale response. It is demonstrated here that this similarity is driven by surface temperature pattern change, not a direct atmospheric circulation response to CO2. This confirms the Warmer get Wetter hypothesis, which emphasizes the role of sea surface temperature pattern change in driving regional tropical precipitation change. Future regional rainfall changes should thus be studied primarily in coupled ocean-atmosphere models. ; Key Points ; Regional tropical rainfall change is driven by surface warming patterns Land-sea warming contrasts can drive tropics-wide circulation change The direct CO2 effect is important for mean rainfall change, but not patterns", + "abstract": "Mechanisms behind regional tropical rainfall responses to CO2 forcing are examined in idealized climate model experiments, traceable to transient forcing scenarios. As previously shown, the pattern of the first-year response of dynamical precipitation change to an abrupt CO2 increase is similar to the century-scale response. It is demonstrated here that this similarity is driven by surface temperature pattern change, not a direct atmospheric circulation response to CO2. This confirms the Warmer get Wetter hypothesis, which emphasizes the role of sea surface temperature pattern change in driving regional tropical precipitation change. Future regional rainfall changes should thus be studied primarily in coupled ocean-atmosphere models. ; ; Regional tropical rainfall change is driven by surface warming patterns Land-sea warming contrasts can drive tropics-wide circulation change The direct CO2 effect is important for mean rainfall change, but not patterns", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1441,7 +1441,7 @@ { "uri": "WOS:000332990500046", "title": "The dependence of transient climate sensitivity and radiative feedbacks on the spatial pattern of ocean heat uptake", - "abstract": "The effect of ocean heat uptake (OHU) on transient global warming is studied in a multimodel framework. Simple heat sinks are prescribed in shallow aquaplanet ocean mixed layers underlying atmospheric general circulation models independently and combined with CO2 forcing. Sinks are localized to either tropical or high latitudes, representing distinct modes of OHU found in coupled simulations. Tropical OHU produces modest cooling at all latitudes, offsetting only a fraction of CO2 warming. High-latitude OHU produces three times more global mean cooling in a strongly polar-amplified pattern. Global sensitivities in each scenario are set primarily by large differences in local shortwave cloud feedbacks, robust across models. Differences in atmospheric energy transport set the pattern of temperature change. Results imply that global and regional warming rates depend sensitively on regional ocean processes setting the OHU pattern, and that equilibrium climate sensitivity cannot be reliably estimated from transient observations. ; Key Points ; Climate response depends strongly on spatial pattern of ocean heat uptake Different radiative feedbacks govern transient and equilibrium CO2 warming Results are robust across an ensemble of aquaplanet climate models", + "abstract": "The effect of ocean heat uptake (OHU) on transient global warming is studied in a multimodel framework. Simple heat sinks are prescribed in shallow aquaplanet ocean mixed layers underlying atmospheric general circulation models independently and combined with CO2 forcing. Sinks are localized to either tropical or high latitudes, representing distinct modes of OHU found in coupled simulations. Tropical OHU produces modest cooling at all latitudes, offsetting only a fraction of CO2 warming. High-latitude OHU produces three times more global mean cooling in a strongly polar-amplified pattern. Global sensitivities in each scenario are set primarily by large differences in local shortwave cloud feedbacks, robust across models. Differences in atmospheric energy transport set the pattern of temperature change. Results imply that global and regional warming rates depend sensitively on regional ocean processes setting the OHU pattern, and that equilibrium climate sensitivity cannot be reliably estimated from transient observations. ; ; Climate response depends strongly on spatial pattern of ocean heat uptake Different radiative feedbacks govern transient and equilibrium CO2 warming Results are robust across an ensemble of aquaplanet climate models", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ diff --git a/data/corpus-simple-etab-50.json b/data/corpus-simple-etab-50.json index 8f43bc0..d02e3a4 100644 --- a/data/corpus-simple-etab-50.json +++ b/data/corpus-simple-etab-50.json @@ -826,6 +826,7 @@ { "uri": "WOS:000334908300014", "title": "Comment on \"The added value to global model projections of climate change by dynamical downscaling: A case study over the continental U. S. using the GISS-ModelE2 and WRF models\" by Racherla et al.", + "abstract": "", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -854,6 +855,7 @@ { "uri": "WOS:000334908300031", "title": "The climatic effects of modifying cirrus clouds in a climate engineering framework", + "abstract": "", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -899,6 +901,7 @@ { "uri": "WOS:000334908300018", "title": "Postlaunch calibration and bias characterization of AMSU-A upper air sounding channels using GPS RO Data", + "abstract": "", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -1063,11 +1066,7 @@ { "uri": "WOS:000332995300006", "title": "Arctic sea ice and atmospheric circulation under the GeoMIP G1 scenario", - "abstract": [ - "We analyze simulated sea ice changes in eight different Earth System Models that have conducted experiment G1 of the Geoengineering Model Intercomparison Project (GeoMIP). The simulated response of balancing abrupt quadrupling of CO2 (abrupt4xCO2) with reduced shortwave radiation successfully moderates annually averaged Arctic temperature rise to about 1 degrees C, with modest changes in seasonal sea ice cycle compared with the preindustrial control simulations (piControl). Changes in summer and autumn sea ice extent are spatially correlated with temperature patterns but much less in winter and spring seasons. However, there are changes of 20% in sea ice concentration in all seasons, and these will induce changes in atmospheric circulation patterns. In summer and autumn, the models consistently simulate less sea ice relative to preindustrial simulations in the Beaufort, Chukchi, East Siberian, and Laptev Seas, and some models show increased sea ice in the Barents/Kara Seas region. Sea ice extent increases in the Greenland Sea, particularly in winter and spring and is to some extent associated with changed sea ice drift. Decreased sea ice cover in winter and spring in the Barents Sea is associated with increased cyclonic activity entering this area under G1. In comparison, the abrupt4xCO2 experiment shows almost total sea ice loss in September and strong correlation with regional temperatures in all seasons consistent with open ocean conditions. The tropospheric circulation displays a Pacific North America pattern-like anomaly with negative phase in G1-piControl and positive phase under abrupt4xCO2-piControl.", - "Key Points", - " Analysis of eight ESM focused on Arctic sea ice and feedback Response of Arctic to G1 geoengineering shows clear regional differences Sea ice is far different in detail under G1 than in pre industrial" - ], + "abstract": "We analyze simulated sea ice changes in eight different Earth System Models that have conducted experiment G1 of the Geoengineering Model Intercomparison Project (GeoMIP). The simulated response of balancing abrupt quadrupling of CO2 (abrupt4xCO2) with reduced shortwave radiation successfully moderates annually averaged Arctic temperature rise to about 1 degrees C, with modest changes in seasonal sea ice cycle compared with the preindustrial control simulations (piControl). Changes in summer and autumn sea ice extent are spatially correlated with temperature patterns but much less in winter and spring seasons. However, there are changes of 20% in sea ice concentration in all seasons, and these will induce changes in atmospheric circulation patterns. In summer and autumn, the models consistently simulate less sea ice relative to preindustrial simulations in the Beaufort, Chukchi, East Siberian, and Laptev Seas, and some models show increased sea ice in the Barents/Kara Seas region. Sea ice extent increases in the Greenland Sea, particularly in winter and spring and is to some extent associated with changed sea ice drift. Decreased sea ice cover in winter and spring in the Barents Sea is associated with increased cyclonic activity entering this area under G1. In comparison, the abrupt4xCO2 experiment shows almost total sea ice loss in September and strong correlation with regional temperatures in all seasons consistent with open ocean conditions. The tropospheric circulation displays a Pacific North America pattern-like anomaly with negative phase in G1-piControl and positive phase under abrupt4xCO2-piControl. ; ; Analysis of eight ESM focused on Arctic sea ice and feedback Response of Arctic to G1 geoengineering shows clear regional differences Sea ice is far different in detail under G1 than in pre industrial", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -1135,10 +1134,7 @@ { "uri": "WOS:000334264900040", "title": "Impact of the Atlanticmeridional overturning circulation on ocean heat storage and transient climate change", - "abstract": [ - "We propose here that the Atlantic meridional overturning circulation (AMOC) plays an important role in setting the effective heat capacity of the World Ocean and thus impacts the pace of transient climate change. The depth and strength of AMOC are shown to be strongly correlated with the depth of heat storage across a suite of state-of-the-art general circulation models (GCMs). In those models with a deeper and stronger AMOC, a smaller portion of the heat anomaly remains in the ocean mixed layer, and consequently, the surface temperature response is delayed. Representations of AMOC differ vastly across the GCMs, providing a major source of intermodel spread in the sea surface temperature (SST) response. A two-layer model fit to the GCMs is used to demonstrate that the intermodel spread in SSTs due to variations in the ocean's effective heat capacity is significant but smaller than the spread due to climate feedbacks.", - "Key Points AMOC plays a key role in setting the effective heat capacity of the World Ocean AMOC properties are correlated with depth of heat storage across CMIP5 GCMs Ocean heat storage is a major source of inter-GCM variability in SST response" - ], + "abstract": "We propose here that the Atlantic meridional overturning circulation (AMOC) plays an important role in setting the effective heat capacity of the World Ocean and thus impacts the pace of transient climate change. The depth and strength of AMOC are shown to be strongly correlated with the depth of heat storage across a suite of state-of-the-art general circulation models (GCMs). In those models with a deeper and stronger AMOC, a smaller portion of the heat anomaly remains in the ocean mixed layer, and consequently, the surface temperature response is delayed. Representations of AMOC differ vastly across the GCMs, providing a major source of intermodel spread in the sea surface temperature (SST) response. A two-layer model fit to the GCMs is used to demonstrate that the intermodel spread in SSTs due to variations in the ocean's effective heat capacity is significant but smaller than the spread due to climate feedbacks. ; AMOC plays a key role in setting the effective heat capacity of the World Ocean AMOC properties are correlated with depth of heat storage across CMIP5 GCMs Ocean heat storage is a major source of inter-GCM variability in SST response", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1171,11 +1167,7 @@ { "uri": "WOS:000334264900041", "title": "Astronomically forced variations in western African rainfall ( 21 N-20 S) during the Last Interglacial period", - "abstract": [ - "This study documents the long-term evolution of western African precipitation during the Last Interglacial (LIG). We compare geochemical records obtained on nine sediment cores from the western African margin to a transient simulation (130-115ka) performed with an ocean-atmosphere general circulation model and insolation as sole forcing. Good agreement between proxy records and model outputs indicates that long-term changes in western African precipitation largely responded to insolation variations during most of the LIG. After an early LIG dry phase (related to high-latitude iceberg melting or dating uncertainties), boreal summer insolation controlled the intensification of the North African monsoon between 127 and 122ka, perhaps facilitating human migrations out of Africa. Equatorial African rainfall slightly increased throughout the LIG in response to increasing annual insolation. East-west contrasting rainfall evolutions at 10-20 degrees S illustrate the complex southern African response, in contrast to more direct responses of North and equatorial western Africa, to insolation forcing.", - "Key Points", - "Insolation controls changes in western African rainfall during most of the LIG Early LIG meltwater may have delayed the North African monsoon intensification Complex response of southern African rainfall with east-west contrasting trends" - ], + "abstract": "This study documents the long-term evolution of western African precipitation during the Last Interglacial (LIG). We compare geochemical records obtained on nine sediment cores from the western African margin to a transient simulation (130-115ka) performed with an ocean-atmosphere general circulation model and insolation as sole forcing. Good agreement between proxy records and model outputs indicates that long-term changes in western African precipitation largely responded to insolation variations during most of the LIG. After an early LIG dry phase (related to high-latitude iceberg melting or dating uncertainties), boreal summer insolation controlled the intensification of the North African monsoon between 127 and 122ka, perhaps facilitating human migrations out of Africa. Equatorial African rainfall slightly increased throughout the LIG in response to increasing annual insolation. East-west contrasting rainfall evolutions at 10-20 degrees S illustrate the complex southern African response, in contrast to more direct responses of North and equatorial western Africa, to insolation forcing. ; ; Insolation controls changes in western African rainfall during most of the LIG Early LIG meltwater may have delayed the North African monsoon intensification Complex response of southern African rainfall with east-west contrasting trends", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1267,11 +1259,7 @@ { "uri": "WOS:000333578800056", "title": "Predictability of the quasi-biennial oscillation and its northern winter teleconnection on seasonal to decadal timescales", - "abstract": [ - "The predictability of the quasi-biennial oscillation (QBO) is examined in initialized climate forecasts extending out to lead times of years. We use initialized retrospective predictions made with coupled ocean-atmosphere climate models that have an internally generated QBO. We demonstrate predictability of the QBO extending more than 3 years into the future, well beyond timescales normally associated with internal atmospheric processes. Correlation scores with observational analyses exceed 0.7 at a lead time of 12months. We also examine the variation of predictability with season and QBO phase and find that skill is lowest in winter. An assessment of perfect predictability suggests that higher skill may be achievable through improved initialization and climate modeling of the QBO, although this may depend on the realism of gravity wave source parameterizations in the models. Finally, we show that skilful prediction of the QBO itself does not guarantee predictability of the extratropical winter teleconnection that is important for surface winter climate prediction.", - "Key Points", - " The QBO is skilfully predicted in seasonal-decadal forecast systems Further improvements in predictions of the QBO are possible The QBO winter surface teleconnection is reproduced with mixed success" - ], + "abstract": "The predictability of the quasi-biennial oscillation (QBO) is examined in initialized climate forecasts extending out to lead times of years. We use initialized retrospective predictions made with coupled ocean-atmosphere climate models that have an internally generated QBO. We demonstrate predictability of the QBO extending more than 3 years into the future, well beyond timescales normally associated with internal atmospheric processes. Correlation scores with observational analyses exceed 0.7 at a lead time of 12months. We also examine the variation of predictability with season and QBO phase and find that skill is lowest in winter. An assessment of perfect predictability suggests that higher skill may be achievable through improved initialization and climate modeling of the QBO, although this may depend on the realism of gravity wave source parameterizations in the models. Finally, we show that skilful prediction of the QBO itself does not guarantee predictability of the extratropical winter teleconnection that is important for surface winter climate prediction. ; ; The QBO is skilfully predicted in seasonal-decadal forecast systems Further improvements in predictions of the QBO are possible The QBO winter surface teleconnection is reproduced with mixed success", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1319,11 +1307,7 @@ { "uri": "WOS:000333578800054", "title": "Modifications of the quasi-biennial oscillation by a geoengineering perturbation of the stratospheric aerosol layer", - "abstract": [ - "This paper examines the impact of geoengineering via stratospheric sulfate aerosol on the quasi-biennial oscillation (QBO) using the NASA Goddard Earth Observing System version 5 Chemistry Climate Model. We performed four 30 year simulations with a continuous injection of sulfur dioxide on the equator at 0 degrees longitude. The four simulations differ by the amount of sulfur dioxide injected (5 Tg/yr and 2.5 Tg/yr) and the altitude of the injection (16km-25km and 22km-25km). We find that such an injection dramatically alters the quasi-biennial oscillation, prolonging the phase of easterly shear with respect to the control simulation. This is caused by the increased aerosol heating and associated warming in the tropical lower stratosphere and higher residual vertical velocity. In the case of maximum perturbation, i.e., highest stratospheric aerosol burden, the lower tropical stratosphere is locked into a permanent westerly QBO phase.", - "Key Points", - " Geoengineering aerosol would prolong the westerly phase of the QBO Large geoengineering stratospheric aerosol injections might interrupt the QBO QBO changes are due to aerosol warming and increased residual vertical velocity" - ], + "abstract": "This paper examines the impact of geoengineering via stratospheric sulfate aerosol on the quasi-biennial oscillation (QBO) using the NASA Goddard Earth Observing System version 5 Chemistry Climate Model. We performed four 30 year simulations with a continuous injection of sulfur dioxide on the equator at 0 degrees longitude. The four simulations differ by the amount of sulfur dioxide injected (5 Tg/yr and 2.5 Tg/yr) and the altitude of the injection (16km-25km and 22km-25km). We find that such an injection dramatically alters the quasi-biennial oscillation, prolonging the phase of easterly shear with respect to the control simulation. This is caused by the increased aerosol heating and associated warming in the tropical lower stratosphere and higher residual vertical velocity. In the case of maximum perturbation, i.e., highest stratospheric aerosol burden, the lower tropical stratosphere is locked into a permanent westerly QBO phase. ; ; Geoengineering aerosol would prolong the westerly phase of the QBO Large geoengineering stratospheric aerosol injections might interrupt the QBO QBO changes are due to aerosol warming and increased residual vertical velocity", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1365,11 +1349,7 @@ { "uri": "WOS:000333578800044", "title": "The implication of radiative forcing and feedback for meridional energy transport", - "abstract": [ - "The distributions of radiative forcing and feedback in the Coupled Model Intercomparison Project phase 5 abrupt4xCO2 and Historical experiments are diagnosed, with a focus on their effects on the zonal mean structure of the top-of-the-atmosphere radiation anomalies and implications for the meridional energy transport. It is found that because the greenhouse gas longwave forcing peaks in the low latitudes, it reinforces the equator-to-pole net radiation gradient and accounts for the increase in the poleward energy transport in both hemispheres under global warming. The shortwave forcing by aerosol, ozone, etc. peaks in the Northern Hemisphere and instead implies an interhemispheric energy transport. Although the water vapor feedback also reinforces the equator-to-pole gradient of the net radiation, the temperature and albedo feedback act against it. The feedback tend to offset the zonal mean radiation anomaly caused by the forcing, although the overall feedback effect on the energy transport is rather uncertain, mainly due to the uncertainty in the cloud feedback.", - "Key Points", - " CO2 forcing increases meridional gradient in net radiation Forcing, rather than feedback, accounts for enhanced poleward energy transport Aerosol forcing accounts for an inter-hemispheric transport anomaly" - ], + "abstract": "The distributions of radiative forcing and feedback in the Coupled Model Intercomparison Project phase 5 abrupt4xCO2 and Historical experiments are diagnosed, with a focus on their effects on the zonal mean structure of the top-of-the-atmosphere radiation anomalies and implications for the meridional energy transport. It is found that because the greenhouse gas longwave forcing peaks in the low latitudes, it reinforces the equator-to-pole net radiation gradient and accounts for the increase in the poleward energy transport in both hemispheres under global warming. The shortwave forcing by aerosol, ozone, etc. peaks in the Northern Hemisphere and instead implies an interhemispheric energy transport. Although the water vapor feedback also reinforces the equator-to-pole gradient of the net radiation, the temperature and albedo feedback act against it. The feedback tend to offset the zonal mean radiation anomaly caused by the forcing, although the overall feedback effect on the energy transport is rather uncertain, mainly due to the uncertainty in the cloud feedback. ; ; CO2 forcing increases meridional gradient in net radiation Forcing, rather than feedback, accounts for enhanced poleward energy transport Aerosol forcing accounts for an inter-hemispheric transport anomaly", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1405,11 +1385,7 @@ { "uri": "WOS:000332995300011", "title": "Evaluation of interpolation techniques for the creation of gridded daily precipitation ( 1 x 1 km2); Cyprus, 1980-2010", - "abstract": [ - "High-resolution gridded daily data sets are essential for natural resource management and the analyses of climate changes and their effects. This study aims to evaluate the performance of 15 simple or complex interpolation techniques in reproducing daily precipitation at a resolution of 1km(2) over topographically complex areas. Methods are tested considering two different sets of observation densities and different rainfall amounts. We used rainfall data that were recorded at 74 and 145 observational stations, respectively, spread over the 5760km(2) of the Republic of Cyprus, in the Eastern Mediterranean. Regression analyses utilizing geographical copredictors and neighboring interpolation techniques were evaluated both in isolation and combined. Linear multiple regression (LMR) and geographically weighted regression methods (GWR) were tested. These included a step-wise selection of covariables, as well as inverse distance weighting (IDW), kriging, and 3D-thin plate splines (TPS). The relative rank of the different techniques changes with different station density and rainfall amounts. Our results indicate that TPS performs well for low station density and large-scale events and also when coupled with regression models. It performs poorly for high station density. The opposite is observed when using IDW. Simple IDW performs best for local events, while a combination of step-wise GWR and IDW proves to be the best method for large-scale events and high station density. This study indicates that the use of step-wise regression with a variable set of geographic parameters can improve the interpolation of large-scale events because it facilitates the representation of local climate dynamics.", - "Key Points", - " Interpolation of daily rainfall data using 15 spatial interpolation methods Relative skill of interpolation techniques depends on observation density High and low rainfall events should be treated with different techniques" - ], + "abstract": "High-resolution gridded daily data sets are essential for natural resource management and the analyses of climate changes and their effects. This study aims to evaluate the performance of 15 simple or complex interpolation techniques in reproducing daily precipitation at a resolution of 1km(2) over topographically complex areas. Methods are tested considering two different sets of observation densities and different rainfall amounts. We used rainfall data that were recorded at 74 and 145 observational stations, respectively, spread over the 5760km(2) of the Republic of Cyprus, in the Eastern Mediterranean. Regression analyses utilizing geographical copredictors and neighboring interpolation techniques were evaluated both in isolation and combined. Linear multiple regression (LMR) and geographically weighted regression methods (GWR) were tested. These included a step-wise selection of covariables, as well as inverse distance weighting (IDW), kriging, and 3D-thin plate splines (TPS). The relative rank of the different techniques changes with different station density and rainfall amounts. Our results indicate that TPS performs well for low station density and large-scale events and also when coupled with regression models. It performs poorly for high station density. The opposite is observed when using IDW. Simple IDW performs best for local events, while a combination of step-wise GWR and IDW proves to be the best method for large-scale events and high station density. This study indicates that the use of step-wise regression with a variable set of geographic parameters can improve the interpolation of large-scale events because it facilitates the representation of local climate dynamics. ; ; Interpolation of daily rainfall data using 15 spatial interpolation methods Relative skill of interpolation techniques depends on observation density High and low rainfall events should be treated with different techniques", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -1507,10 +1483,7 @@ { "uri": "WOS:000333885700023", "title": "Cirrus cloud susceptibility to the injection of ice nuclei in the upper troposphere", - "abstract": [ - "Due to their net warming effect, cirrus clouds play a crucial role in the climate system. A recently proposed climate engineering mechanism (CEM) intends to reduce high cloud cover by seeding cirrus clouds with efficient ice nuclei (IN) and therefore cool climate. Here, the susceptibility of cirrus clouds to the injection of ice nuclei in the upper troposphere is investigated in the extended Community Atmospheric Model version 5 (CAM5). Due to large uncertainties associated with the dominant ice nucleation mechanism in cirrus clouds, different control cases were simulated. In addition to pure homogeneous and heterogeneous nucleation, cases with competition between homogeneous and heterogeneous nucleation and different fractions of mineral dust active as IN were considered. Whereas seeding in the pure heterogeneous case leads to a strong warming due to overseeding, an optimal seeding IN concentration of approximately 18 l(-1) was found for the other cases. For the optimal seeding concentration, a reduction in the net cloud forcing (NCF) of up to 2 W m(-2) was simulated, corresponding to a strong cooling effect. To optimize the cooling and minimize the amount of seeding material, globally nonuniform seeding strategies were tested, with minimal seeding in the summer hemisphere and in the tropics. With seeding applied to less than half the globe, an even stronger reduction in the NCF was achieved. This suggests that the CEM could work for an atmosphere even with considerable heterogeneous ice nucleation and that the desired cooling could be obtained without seeding the entire globe.", - "Key Points Cirrus cloud seeding in the upper troposphere was simulated in CAM5 Both cirrus cloud susceptibility and short-term climate response were analyzed Even globally non-uniform injection of IN leads to the desired cooling" - ], + "abstract": "Due to their net warming effect, cirrus clouds play a crucial role in the climate system. A recently proposed climate engineering mechanism (CEM) intends to reduce high cloud cover by seeding cirrus clouds with efficient ice nuclei (IN) and therefore cool climate. Here, the susceptibility of cirrus clouds to the injection of ice nuclei in the upper troposphere is investigated in the extended Community Atmospheric Model version 5 (CAM5). Due to large uncertainties associated with the dominant ice nucleation mechanism in cirrus clouds, different control cases were simulated. In addition to pure homogeneous and heterogeneous nucleation, cases with competition between homogeneous and heterogeneous nucleation and different fractions of mineral dust active as IN were considered. Whereas seeding in the pure heterogeneous case leads to a strong warming due to overseeding, an optimal seeding IN concentration of approximately 18 l(-1) was found for the other cases. For the optimal seeding concentration, a reduction in the net cloud forcing (NCF) of up to 2 W m(-2) was simulated, corresponding to a strong cooling effect. To optimize the cooling and minimize the amount of seeding material, globally nonuniform seeding strategies were tested, with minimal seeding in the summer hemisphere and in the tropics. With seeding applied to less than half the globe, an even stronger reduction in the NCF was achieved. This suggests that the CEM could work for an atmosphere even with considerable heterogeneous ice nucleation and that the desired cooling could be obtained without seeding the entire globe. ; Cirrus cloud seeding in the upper troposphere was simulated in CAM5 Both cirrus cloud susceptibility and short-term climate response were analyzed Even globally non-uniform injection of IN leads to the desired cooling", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -1552,11 +1525,7 @@ { "uri": "WOS:000333885700020", "title": "What controls the interannual variation of the wet season onsets over the Amazon?", - "abstract": [ - "Previous studies have established that sea surface temperature anomalies (SSTAs) in the tropical Pacific and Atlantic are the main forcing of the interannual variation of the wet season onsets in the Amazon. However, this variation appears to be complex and not uniquely determined by SSTAs. What causes such a complexity and to what extent the interannual variation of the wet season onsets is predictable remain unclear. This study suggests that such a complex relationship is the result of several competing processes, which are nonlinearly related to the SSTAs. In particular, three dry season conditions are crucial for determining interannual variation of the wet season onset. (i) A poleward shift of the Southern Hemisphere subtropical jet (SHSJ) over the South American sector, initiated from a wave train-like structure possibly forced by south central Pacific SST patterns, can prevent cold frontal systems from moving northward into the Amazon. This delays cold air incursion and results in late wet season onset over the southern Amazon. (ii) An anomalous anticyclonic center, which enhances westerly wind at 850hPa over the southern Amazon and also the South American low-level jets, leads to moisture export from the southern Amazon to La Plata basin and reduces convective systems that provide elevated diabatic heating. (iii) Smaller convective available potential energy (CAPE) limits local thermodynamically driven convection. Based on the stepwise and partial least squares regressions, these three selected preseasonal conditions (Nino 4, SHSJ, and CAPE) can explain 57% of the total variance of the wet season onset.", - "Key Points", - " The wet season onset over the Amazon is not uniquely deterimined by SSTAs A poleward SHSJ, enhanced U850, and lower CAPE are crucial for delayed onset Selected conditions can explain 57% of the total variance" - ], + "abstract": "Previous studies have established that sea surface temperature anomalies (SSTAs) in the tropical Pacific and Atlantic are the main forcing of the interannual variation of the wet season onsets in the Amazon. However, this variation appears to be complex and not uniquely determined by SSTAs. What causes such a complexity and to what extent the interannual variation of the wet season onsets is predictable remain unclear. This study suggests that such a complex relationship is the result of several competing processes, which are nonlinearly related to the SSTAs. In particular, three dry season conditions are crucial for determining interannual variation of the wet season onset. (i) A poleward shift of the Southern Hemisphere subtropical jet (SHSJ) over the South American sector, initiated from a wave train-like structure possibly forced by south central Pacific SST patterns, can prevent cold frontal systems from moving northward into the Amazon. This delays cold air incursion and results in late wet season onset over the southern Amazon. (ii) An anomalous anticyclonic center, which enhances westerly wind at 850hPa over the southern Amazon and also the South American low-level jets, leads to moisture export from the southern Amazon to La Plata basin and reduces convective systems that provide elevated diabatic heating. (iii) Smaller convective available potential energy (CAPE) limits local thermodynamically driven convection. Based on the stepwise and partial least squares regressions, these three selected preseasonal conditions (Nino 4, SHSJ, and CAPE) can explain 57% of the total variance of the wet season onset. ; ; The wet season onset over the Amazon is not uniquely deterimined by SSTAs A poleward SHSJ, enhanced U850, and lower CAPE are crucial for delayed onset Selected conditions can explain 57% of the total variance", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -1748,11 +1717,7 @@ { "uri": "WOS:000332991000059", "title": "Surface warming patterns drive tropical rainfall pattern responses to CO2 forcing on all timescales", - "abstract": [ - "Mechanisms behind regional tropical rainfall responses to CO2 forcing are examined in idealized climate model experiments, traceable to transient forcing scenarios. As previously shown, the pattern of the first-year response of dynamical precipitation change to an abrupt CO2 increase is similar to the century-scale response. It is demonstrated here that this similarity is driven by surface temperature pattern change, not a direct atmospheric circulation response to CO2. This confirms the Warmer get Wetter hypothesis, which emphasizes the role of sea surface temperature pattern change in driving regional tropical precipitation change. Future regional rainfall changes should thus be studied primarily in coupled ocean-atmosphere models.", - "Key Points", - " Regional tropical rainfall change is driven by surface warming patterns Land-sea warming contrasts can drive tropics-wide circulation change The direct CO2 effect is important for mean rainfall change, but not patterns" - ], + "abstract": "Mechanisms behind regional tropical rainfall responses to CO2 forcing are examined in idealized climate model experiments, traceable to transient forcing scenarios. As previously shown, the pattern of the first-year response of dynamical precipitation change to an abrupt CO2 increase is similar to the century-scale response. It is demonstrated here that this similarity is driven by surface temperature pattern change, not a direct atmospheric circulation response to CO2. This confirms the Warmer get Wetter hypothesis, which emphasizes the role of sea surface temperature pattern change in driving regional tropical precipitation change. Future regional rainfall changes should thus be studied primarily in coupled ocean-atmosphere models. ; ; Regional tropical rainfall change is driven by surface warming patterns Land-sea warming contrasts can drive tropics-wide circulation change The direct CO2 effect is important for mean rainfall change, but not patterns", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1822,11 +1787,7 @@ { "uri": "WOS:000332990500046", "title": "The dependence of transient climate sensitivity and radiative feedbacks on the spatial pattern of ocean heat uptake", - "abstract": [ - "The effect of ocean heat uptake (OHU) on transient global warming is studied in a multimodel framework. Simple heat sinks are prescribed in shallow aquaplanet ocean mixed layers underlying atmospheric general circulation models independently and combined with CO2 forcing. Sinks are localized to either tropical or high latitudes, representing distinct modes of OHU found in coupled simulations. Tropical OHU produces modest cooling at all latitudes, offsetting only a fraction of CO2 warming. High-latitude OHU produces three times more global mean cooling in a strongly polar-amplified pattern. Global sensitivities in each scenario are set primarily by large differences in local shortwave cloud feedbacks, robust across models. Differences in atmospheric energy transport set the pattern of temperature change. Results imply that global and regional warming rates depend sensitively on regional ocean processes setting the OHU pattern, and that equilibrium climate sensitivity cannot be reliably estimated from transient observations.", - "Key Points", - "Climate response depends strongly on spatial pattern of ocean heat uptake Different radiative feedbacks govern transient and equilibrium CO2 warming Results are robust across an ensemble of aquaplanet climate models" - ], + "abstract": "The effect of ocean heat uptake (OHU) on transient global warming is studied in a multimodel framework. Simple heat sinks are prescribed in shallow aquaplanet ocean mixed layers underlying atmospheric general circulation models independently and combined with CO2 forcing. Sinks are localized to either tropical or high latitudes, representing distinct modes of OHU found in coupled simulations. Tropical OHU produces modest cooling at all latitudes, offsetting only a fraction of CO2 warming. High-latitude OHU produces three times more global mean cooling in a strongly polar-amplified pattern. Global sensitivities in each scenario are set primarily by large differences in local shortwave cloud feedbacks, robust across models. Differences in atmospheric energy transport set the pattern of temperature change. Results imply that global and regional warming rates depend sensitively on regional ocean processes setting the OHU pattern, and that equilibrium climate sensitivity cannot be reliably estimated from transient observations. ; ; Climate response depends strongly on spatial pattern of ocean heat uptake Different radiative feedbacks govern transient and equilibrium CO2 warming Results are robust across an ensemble of aquaplanet climate models", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -2115,6 +2076,7 @@ { "uri": "WOS:000334908300017", "title": "A multimodel examination of climate extremes in an idealized geoengineering experiment", + "abstract": "", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -2177,6 +2139,7 @@ { "uri": "WOS:000334908300040", "title": "Ammonia emissions in the United States, European Union, and China derived by high-resolution inversion of ammonium wet deposition data: Interpretation with a new agricultural emissions inventory (MASAGE_NH3)", + "abstract": "", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ diff --git a/data/corpus-simple-instituts-50.json b/data/corpus-simple-instituts-50.json index f2c7b9b..2c45263 100644 --- a/data/corpus-simple-instituts-50.json +++ b/data/corpus-simple-instituts-50.json @@ -862,6 +862,7 @@ { "uri": "WOS:000334908300014", "title": "Comment on \"The added value to global model projections of climate change by dynamical downscaling: A case study over the continental U. S. using the GISS-ModelE2 and WRF models\" by Racherla et al.", + "abstract": "", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -892,6 +893,7 @@ { "uri": "WOS:000334908300031", "title": "The climatic effects of modifying cirrus clouds in a climate engineering framework", + "abstract": "", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -939,6 +941,7 @@ { "uri": "WOS:000334908300018", "title": "Postlaunch calibration and bias characterization of AMSU-A upper air sounding channels using GPS RO Data", + "abstract": "", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -1111,11 +1114,7 @@ { "uri": "WOS:000332995300006", "title": "Arctic sea ice and atmospheric circulation under the GeoMIP G1 scenario", - "abstract": [ - "We analyze simulated sea ice changes in eight different Earth System Models that have conducted experiment G1 of the Geoengineering Model Intercomparison Project (GeoMIP). The simulated response of balancing abrupt quadrupling of CO2 (abrupt4xCO2) with reduced shortwave radiation successfully moderates annually averaged Arctic temperature rise to about 1 degrees C, with modest changes in seasonal sea ice cycle compared with the preindustrial control simulations (piControl). Changes in summer and autumn sea ice extent are spatially correlated with temperature patterns but much less in winter and spring seasons. However, there are changes of 20% in sea ice concentration in all seasons, and these will induce changes in atmospheric circulation patterns. In summer and autumn, the models consistently simulate less sea ice relative to preindustrial simulations in the Beaufort, Chukchi, East Siberian, and Laptev Seas, and some models show increased sea ice in the Barents/Kara Seas region. Sea ice extent increases in the Greenland Sea, particularly in winter and spring and is to some extent associated with changed sea ice drift. Decreased sea ice cover in winter and spring in the Barents Sea is associated with increased cyclonic activity entering this area under G1. In comparison, the abrupt4xCO2 experiment shows almost total sea ice loss in September and strong correlation with regional temperatures in all seasons consistent with open ocean conditions. The tropospheric circulation displays a Pacific North America pattern-like anomaly with negative phase in G1-piControl and positive phase under abrupt4xCO2-piControl.", - "Key Points", - " Analysis of eight ESM focused on Arctic sea ice and feedback Response of Arctic to G1 geoengineering shows clear regional differences Sea ice is far different in detail under G1 than in pre industrial" - ], + "abstract": "We analyze simulated sea ice changes in eight different Earth System Models that have conducted experiment G1 of the Geoengineering Model Intercomparison Project (GeoMIP). The simulated response of balancing abrupt quadrupling of CO2 (abrupt4xCO2) with reduced shortwave radiation successfully moderates annually averaged Arctic temperature rise to about 1 degrees C, with modest changes in seasonal sea ice cycle compared with the preindustrial control simulations (piControl). Changes in summer and autumn sea ice extent are spatially correlated with temperature patterns but much less in winter and spring seasons. However, there are changes of 20% in sea ice concentration in all seasons, and these will induce changes in atmospheric circulation patterns. In summer and autumn, the models consistently simulate less sea ice relative to preindustrial simulations in the Beaufort, Chukchi, East Siberian, and Laptev Seas, and some models show increased sea ice in the Barents/Kara Seas region. Sea ice extent increases in the Greenland Sea, particularly in winter and spring and is to some extent associated with changed sea ice drift. Decreased sea ice cover in winter and spring in the Barents Sea is associated with increased cyclonic activity entering this area under G1. In comparison, the abrupt4xCO2 experiment shows almost total sea ice loss in September and strong correlation with regional temperatures in all seasons consistent with open ocean conditions. The tropospheric circulation displays a Pacific North America pattern-like anomaly with negative phase in G1-piControl and positive phase under abrupt4xCO2-piControl. ; ; Analysis of eight ESM focused on Arctic sea ice and feedback Response of Arctic to G1 geoengineering shows clear regional differences Sea ice is far different in detail under G1 than in pre industrial", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -1185,10 +1184,7 @@ { "uri": "WOS:000334264900040", "title": "Impact of the Atlanticmeridional overturning circulation on ocean heat storage and transient climate change", - "abstract": [ - "We propose here that the Atlantic meridional overturning circulation (AMOC) plays an important role in setting the effective heat capacity of the World Ocean and thus impacts the pace of transient climate change. The depth and strength of AMOC are shown to be strongly correlated with the depth of heat storage across a suite of state-of-the-art general circulation models (GCMs). In those models with a deeper and stronger AMOC, a smaller portion of the heat anomaly remains in the ocean mixed layer, and consequently, the surface temperature response is delayed. Representations of AMOC differ vastly across the GCMs, providing a major source of intermodel spread in the sea surface temperature (SST) response. A two-layer model fit to the GCMs is used to demonstrate that the intermodel spread in SSTs due to variations in the ocean's effective heat capacity is significant but smaller than the spread due to climate feedbacks.", - "Key Points AMOC plays a key role in setting the effective heat capacity of the World Ocean AMOC properties are correlated with depth of heat storage across CMIP5 GCMs Ocean heat storage is a major source of inter-GCM variability in SST response" - ], + "abstract": "We propose here that the Atlantic meridional overturning circulation (AMOC) plays an important role in setting the effective heat capacity of the World Ocean and thus impacts the pace of transient climate change. The depth and strength of AMOC are shown to be strongly correlated with the depth of heat storage across a suite of state-of-the-art general circulation models (GCMs). In those models with a deeper and stronger AMOC, a smaller portion of the heat anomaly remains in the ocean mixed layer, and consequently, the surface temperature response is delayed. Representations of AMOC differ vastly across the GCMs, providing a major source of intermodel spread in the sea surface temperature (SST) response. A two-layer model fit to the GCMs is used to demonstrate that the intermodel spread in SSTs due to variations in the ocean's effective heat capacity is significant but smaller than the spread due to climate feedbacks. ; AMOC plays a key role in setting the effective heat capacity of the World Ocean AMOC properties are correlated with depth of heat storage across CMIP5 GCMs Ocean heat storage is a major source of inter-GCM variability in SST response", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1223,11 +1219,7 @@ { "uri": "WOS:000334264900041", "title": "Astronomically forced variations in western African rainfall ( 21 N-20 S) during the Last Interglacial period", - "abstract": [ - "This study documents the long-term evolution of western African precipitation during the Last Interglacial (LIG). We compare geochemical records obtained on nine sediment cores from the western African margin to a transient simulation (130-115ka) performed with an ocean-atmosphere general circulation model and insolation as sole forcing. Good agreement between proxy records and model outputs indicates that long-term changes in western African precipitation largely responded to insolation variations during most of the LIG. After an early LIG dry phase (related to high-latitude iceberg melting or dating uncertainties), boreal summer insolation controlled the intensification of the North African monsoon between 127 and 122ka, perhaps facilitating human migrations out of Africa. Equatorial African rainfall slightly increased throughout the LIG in response to increasing annual insolation. East-west contrasting rainfall evolutions at 10-20 degrees S illustrate the complex southern African response, in contrast to more direct responses of North and equatorial western Africa, to insolation forcing.", - "Key Points", - "Insolation controls changes in western African rainfall during most of the LIG Early LIG meltwater may have delayed the North African monsoon intensification Complex response of southern African rainfall with east-west contrasting trends" - ], + "abstract": "This study documents the long-term evolution of western African precipitation during the Last Interglacial (LIG). We compare geochemical records obtained on nine sediment cores from the western African margin to a transient simulation (130-115ka) performed with an ocean-atmosphere general circulation model and insolation as sole forcing. Good agreement between proxy records and model outputs indicates that long-term changes in western African precipitation largely responded to insolation variations during most of the LIG. After an early LIG dry phase (related to high-latitude iceberg melting or dating uncertainties), boreal summer insolation controlled the intensification of the North African monsoon between 127 and 122ka, perhaps facilitating human migrations out of Africa. Equatorial African rainfall slightly increased throughout the LIG in response to increasing annual insolation. East-west contrasting rainfall evolutions at 10-20 degrees S illustrate the complex southern African response, in contrast to more direct responses of North and equatorial western Africa, to insolation forcing. ; ; Insolation controls changes in western African rainfall during most of the LIG Early LIG meltwater may have delayed the North African monsoon intensification Complex response of southern African rainfall with east-west contrasting trends", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1323,11 +1315,7 @@ { "uri": "WOS:000333578800056", "title": "Predictability of the quasi-biennial oscillation and its northern winter teleconnection on seasonal to decadal timescales", - "abstract": [ - "The predictability of the quasi-biennial oscillation (QBO) is examined in initialized climate forecasts extending out to lead times of years. We use initialized retrospective predictions made with coupled ocean-atmosphere climate models that have an internally generated QBO. We demonstrate predictability of the QBO extending more than 3 years into the future, well beyond timescales normally associated with internal atmospheric processes. Correlation scores with observational analyses exceed 0.7 at a lead time of 12months. We also examine the variation of predictability with season and QBO phase and find that skill is lowest in winter. An assessment of perfect predictability suggests that higher skill may be achievable through improved initialization and climate modeling of the QBO, although this may depend on the realism of gravity wave source parameterizations in the models. Finally, we show that skilful prediction of the QBO itself does not guarantee predictability of the extratropical winter teleconnection that is important for surface winter climate prediction.", - "Key Points", - " The QBO is skilfully predicted in seasonal-decadal forecast systems Further improvements in predictions of the QBO are possible The QBO winter surface teleconnection is reproduced with mixed success" - ], + "abstract": "The predictability of the quasi-biennial oscillation (QBO) is examined in initialized climate forecasts extending out to lead times of years. We use initialized retrospective predictions made with coupled ocean-atmosphere climate models that have an internally generated QBO. We demonstrate predictability of the QBO extending more than 3 years into the future, well beyond timescales normally associated with internal atmospheric processes. Correlation scores with observational analyses exceed 0.7 at a lead time of 12months. We also examine the variation of predictability with season and QBO phase and find that skill is lowest in winter. An assessment of perfect predictability suggests that higher skill may be achievable through improved initialization and climate modeling of the QBO, although this may depend on the realism of gravity wave source parameterizations in the models. Finally, we show that skilful prediction of the QBO itself does not guarantee predictability of the extratropical winter teleconnection that is important for surface winter climate prediction. ; ; The QBO is skilfully predicted in seasonal-decadal forecast systems Further improvements in predictions of the QBO are possible The QBO winter surface teleconnection is reproduced with mixed success", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1377,11 +1365,7 @@ { "uri": "WOS:000333578800054", "title": "Modifications of the quasi-biennial oscillation by a geoengineering perturbation of the stratospheric aerosol layer", - "abstract": [ - "This paper examines the impact of geoengineering via stratospheric sulfate aerosol on the quasi-biennial oscillation (QBO) using the NASA Goddard Earth Observing System version 5 Chemistry Climate Model. We performed four 30 year simulations with a continuous injection of sulfur dioxide on the equator at 0 degrees longitude. The four simulations differ by the amount of sulfur dioxide injected (5 Tg/yr and 2.5 Tg/yr) and the altitude of the injection (16km-25km and 22km-25km). We find that such an injection dramatically alters the quasi-biennial oscillation, prolonging the phase of easterly shear with respect to the control simulation. This is caused by the increased aerosol heating and associated warming in the tropical lower stratosphere and higher residual vertical velocity. In the case of maximum perturbation, i.e., highest stratospheric aerosol burden, the lower tropical stratosphere is locked into a permanent westerly QBO phase.", - "Key Points", - " Geoengineering aerosol would prolong the westerly phase of the QBO Large geoengineering stratospheric aerosol injections might interrupt the QBO QBO changes are due to aerosol warming and increased residual vertical velocity" - ], + "abstract": "This paper examines the impact of geoengineering via stratospheric sulfate aerosol on the quasi-biennial oscillation (QBO) using the NASA Goddard Earth Observing System version 5 Chemistry Climate Model. We performed four 30 year simulations with a continuous injection of sulfur dioxide on the equator at 0 degrees longitude. The four simulations differ by the amount of sulfur dioxide injected (5 Tg/yr and 2.5 Tg/yr) and the altitude of the injection (16km-25km and 22km-25km). We find that such an injection dramatically alters the quasi-biennial oscillation, prolonging the phase of easterly shear with respect to the control simulation. This is caused by the increased aerosol heating and associated warming in the tropical lower stratosphere and higher residual vertical velocity. In the case of maximum perturbation, i.e., highest stratospheric aerosol burden, the lower tropical stratosphere is locked into a permanent westerly QBO phase. ; ; Geoengineering aerosol would prolong the westerly phase of the QBO Large geoengineering stratospheric aerosol injections might interrupt the QBO QBO changes are due to aerosol warming and increased residual vertical velocity", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1425,11 +1409,7 @@ { "uri": "WOS:000333578800044", "title": "The implication of radiative forcing and feedback for meridional energy transport", - "abstract": [ - "The distributions of radiative forcing and feedback in the Coupled Model Intercomparison Project phase 5 abrupt4xCO2 and Historical experiments are diagnosed, with a focus on their effects on the zonal mean structure of the top-of-the-atmosphere radiation anomalies and implications for the meridional energy transport. It is found that because the greenhouse gas longwave forcing peaks in the low latitudes, it reinforces the equator-to-pole net radiation gradient and accounts for the increase in the poleward energy transport in both hemispheres under global warming. The shortwave forcing by aerosol, ozone, etc. peaks in the Northern Hemisphere and instead implies an interhemispheric energy transport. Although the water vapor feedback also reinforces the equator-to-pole gradient of the net radiation, the temperature and albedo feedback act against it. The feedback tend to offset the zonal mean radiation anomaly caused by the forcing, although the overall feedback effect on the energy transport is rather uncertain, mainly due to the uncertainty in the cloud feedback.", - "Key Points", - " CO2 forcing increases meridional gradient in net radiation Forcing, rather than feedback, accounts for enhanced poleward energy transport Aerosol forcing accounts for an inter-hemispheric transport anomaly" - ], + "abstract": "The distributions of radiative forcing and feedback in the Coupled Model Intercomparison Project phase 5 abrupt4xCO2 and Historical experiments are diagnosed, with a focus on their effects on the zonal mean structure of the top-of-the-atmosphere radiation anomalies and implications for the meridional energy transport. It is found that because the greenhouse gas longwave forcing peaks in the low latitudes, it reinforces the equator-to-pole net radiation gradient and accounts for the increase in the poleward energy transport in both hemispheres under global warming. The shortwave forcing by aerosol, ozone, etc. peaks in the Northern Hemisphere and instead implies an interhemispheric energy transport. Although the water vapor feedback also reinforces the equator-to-pole gradient of the net radiation, the temperature and albedo feedback act against it. The feedback tend to offset the zonal mean radiation anomaly caused by the forcing, although the overall feedback effect on the energy transport is rather uncertain, mainly due to the uncertainty in the cloud feedback. ; ; CO2 forcing increases meridional gradient in net radiation Forcing, rather than feedback, accounts for enhanced poleward energy transport Aerosol forcing accounts for an inter-hemispheric transport anomaly", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1467,11 +1447,7 @@ { "uri": "WOS:000332995300011", "title": "Evaluation of interpolation techniques for the creation of gridded daily precipitation ( 1 x 1 km2); Cyprus, 1980-2010", - "abstract": [ - "High-resolution gridded daily data sets are essential for natural resource management and the analyses of climate changes and their effects. This study aims to evaluate the performance of 15 simple or complex interpolation techniques in reproducing daily precipitation at a resolution of 1km(2) over topographically complex areas. Methods are tested considering two different sets of observation densities and different rainfall amounts. We used rainfall data that were recorded at 74 and 145 observational stations, respectively, spread over the 5760km(2) of the Republic of Cyprus, in the Eastern Mediterranean. Regression analyses utilizing geographical copredictors and neighboring interpolation techniques were evaluated both in isolation and combined. Linear multiple regression (LMR) and geographically weighted regression methods (GWR) were tested. These included a step-wise selection of covariables, as well as inverse distance weighting (IDW), kriging, and 3D-thin plate splines (TPS). The relative rank of the different techniques changes with different station density and rainfall amounts. Our results indicate that TPS performs well for low station density and large-scale events and also when coupled with regression models. It performs poorly for high station density. The opposite is observed when using IDW. Simple IDW performs best for local events, while a combination of step-wise GWR and IDW proves to be the best method for large-scale events and high station density. This study indicates that the use of step-wise regression with a variable set of geographic parameters can improve the interpolation of large-scale events because it facilitates the representation of local climate dynamics.", - "Key Points", - " Interpolation of daily rainfall data using 15 spatial interpolation methods Relative skill of interpolation techniques depends on observation density High and low rainfall events should be treated with different techniques" - ], + "abstract": "High-resolution gridded daily data sets are essential for natural resource management and the analyses of climate changes and their effects. This study aims to evaluate the performance of 15 simple or complex interpolation techniques in reproducing daily precipitation at a resolution of 1km(2) over topographically complex areas. Methods are tested considering two different sets of observation densities and different rainfall amounts. We used rainfall data that were recorded at 74 and 145 observational stations, respectively, spread over the 5760km(2) of the Republic of Cyprus, in the Eastern Mediterranean. Regression analyses utilizing geographical copredictors and neighboring interpolation techniques were evaluated both in isolation and combined. Linear multiple regression (LMR) and geographically weighted regression methods (GWR) were tested. These included a step-wise selection of covariables, as well as inverse distance weighting (IDW), kriging, and 3D-thin plate splines (TPS). The relative rank of the different techniques changes with different station density and rainfall amounts. Our results indicate that TPS performs well for low station density and large-scale events and also when coupled with regression models. It performs poorly for high station density. The opposite is observed when using IDW. Simple IDW performs best for local events, while a combination of step-wise GWR and IDW proves to be the best method for large-scale events and high station density. This study indicates that the use of step-wise regression with a variable set of geographic parameters can improve the interpolation of large-scale events because it facilitates the representation of local climate dynamics. ; ; Interpolation of daily rainfall data using 15 spatial interpolation methods Relative skill of interpolation techniques depends on observation density High and low rainfall events should be treated with different techniques", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -1573,10 +1549,7 @@ { "uri": "WOS:000333885700023", "title": "Cirrus cloud susceptibility to the injection of ice nuclei in the upper troposphere", - "abstract": [ - "Due to their net warming effect, cirrus clouds play a crucial role in the climate system. A recently proposed climate engineering mechanism (CEM) intends to reduce high cloud cover by seeding cirrus clouds with efficient ice nuclei (IN) and therefore cool climate. Here, the susceptibility of cirrus clouds to the injection of ice nuclei in the upper troposphere is investigated in the extended Community Atmospheric Model version 5 (CAM5). Due to large uncertainties associated with the dominant ice nucleation mechanism in cirrus clouds, different control cases were simulated. In addition to pure homogeneous and heterogeneous nucleation, cases with competition between homogeneous and heterogeneous nucleation and different fractions of mineral dust active as IN were considered. Whereas seeding in the pure heterogeneous case leads to a strong warming due to overseeding, an optimal seeding IN concentration of approximately 18 l(-1) was found for the other cases. For the optimal seeding concentration, a reduction in the net cloud forcing (NCF) of up to 2 W m(-2) was simulated, corresponding to a strong cooling effect. To optimize the cooling and minimize the amount of seeding material, globally nonuniform seeding strategies were tested, with minimal seeding in the summer hemisphere and in the tropics. With seeding applied to less than half the globe, an even stronger reduction in the NCF was achieved. This suggests that the CEM could work for an atmosphere even with considerable heterogeneous ice nucleation and that the desired cooling could be obtained without seeding the entire globe.", - "Key Points Cirrus cloud seeding in the upper troposphere was simulated in CAM5 Both cirrus cloud susceptibility and short-term climate response were analyzed Even globally non-uniform injection of IN leads to the desired cooling" - ], + "abstract": "Due to their net warming effect, cirrus clouds play a crucial role in the climate system. A recently proposed climate engineering mechanism (CEM) intends to reduce high cloud cover by seeding cirrus clouds with efficient ice nuclei (IN) and therefore cool climate. Here, the susceptibility of cirrus clouds to the injection of ice nuclei in the upper troposphere is investigated in the extended Community Atmospheric Model version 5 (CAM5). Due to large uncertainties associated with the dominant ice nucleation mechanism in cirrus clouds, different control cases were simulated. In addition to pure homogeneous and heterogeneous nucleation, cases with competition between homogeneous and heterogeneous nucleation and different fractions of mineral dust active as IN were considered. Whereas seeding in the pure heterogeneous case leads to a strong warming due to overseeding, an optimal seeding IN concentration of approximately 18 l(-1) was found for the other cases. For the optimal seeding concentration, a reduction in the net cloud forcing (NCF) of up to 2 W m(-2) was simulated, corresponding to a strong cooling effect. To optimize the cooling and minimize the amount of seeding material, globally nonuniform seeding strategies were tested, with minimal seeding in the summer hemisphere and in the tropics. With seeding applied to less than half the globe, an even stronger reduction in the NCF was achieved. This suggests that the CEM could work for an atmosphere even with considerable heterogeneous ice nucleation and that the desired cooling could be obtained without seeding the entire globe. ; Cirrus cloud seeding in the upper troposphere was simulated in CAM5 Both cirrus cloud susceptibility and short-term climate response were analyzed Even globally non-uniform injection of IN leads to the desired cooling", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -1620,11 +1593,7 @@ { "uri": "WOS:000333885700020", "title": "What controls the interannual variation of the wet season onsets over the Amazon?", - "abstract": [ - "Previous studies have established that sea surface temperature anomalies (SSTAs) in the tropical Pacific and Atlantic are the main forcing of the interannual variation of the wet season onsets in the Amazon. However, this variation appears to be complex and not uniquely determined by SSTAs. What causes such a complexity and to what extent the interannual variation of the wet season onsets is predictable remain unclear. This study suggests that such a complex relationship is the result of several competing processes, which are nonlinearly related to the SSTAs. In particular, three dry season conditions are crucial for determining interannual variation of the wet season onset. (i) A poleward shift of the Southern Hemisphere subtropical jet (SHSJ) over the South American sector, initiated from a wave train-like structure possibly forced by south central Pacific SST patterns, can prevent cold frontal systems from moving northward into the Amazon. This delays cold air incursion and results in late wet season onset over the southern Amazon. (ii) An anomalous anticyclonic center, which enhances westerly wind at 850hPa over the southern Amazon and also the South American low-level jets, leads to moisture export from the southern Amazon to La Plata basin and reduces convective systems that provide elevated diabatic heating. (iii) Smaller convective available potential energy (CAPE) limits local thermodynamically driven convection. Based on the stepwise and partial least squares regressions, these three selected preseasonal conditions (Nino 4, SHSJ, and CAPE) can explain 57% of the total variance of the wet season onset.", - "Key Points", - " The wet season onset over the Amazon is not uniquely deterimined by SSTAs A poleward SHSJ, enhanced U850, and lower CAPE are crucial for delayed onset Selected conditions can explain 57% of the total variance" - ], + "abstract": "Previous studies have established that sea surface temperature anomalies (SSTAs) in the tropical Pacific and Atlantic are the main forcing of the interannual variation of the wet season onsets in the Amazon. However, this variation appears to be complex and not uniquely determined by SSTAs. What causes such a complexity and to what extent the interannual variation of the wet season onsets is predictable remain unclear. This study suggests that such a complex relationship is the result of several competing processes, which are nonlinearly related to the SSTAs. In particular, three dry season conditions are crucial for determining interannual variation of the wet season onset. (i) A poleward shift of the Southern Hemisphere subtropical jet (SHSJ) over the South American sector, initiated from a wave train-like structure possibly forced by south central Pacific SST patterns, can prevent cold frontal systems from moving northward into the Amazon. This delays cold air incursion and results in late wet season onset over the southern Amazon. (ii) An anomalous anticyclonic center, which enhances westerly wind at 850hPa over the southern Amazon and also the South American low-level jets, leads to moisture export from the southern Amazon to La Plata basin and reduces convective systems that provide elevated diabatic heating. (iii) Smaller convective available potential energy (CAPE) limits local thermodynamically driven convection. Based on the stepwise and partial least squares regressions, these three selected preseasonal conditions (Nino 4, SHSJ, and CAPE) can explain 57% of the total variance of the wet season onset. ; ; The wet season onset over the Amazon is not uniquely deterimined by SSTAs A poleward SHSJ, enhanced U850, and lower CAPE are crucial for delayed onset Selected conditions can explain 57% of the total variance", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -1824,11 +1793,7 @@ { "uri": "WOS:000332991000059", "title": "Surface warming patterns drive tropical rainfall pattern responses to CO2 forcing on all timescales", - "abstract": [ - "Mechanisms behind regional tropical rainfall responses to CO2 forcing are examined in idealized climate model experiments, traceable to transient forcing scenarios. As previously shown, the pattern of the first-year response of dynamical precipitation change to an abrupt CO2 increase is similar to the century-scale response. It is demonstrated here that this similarity is driven by surface temperature pattern change, not a direct atmospheric circulation response to CO2. This confirms the Warmer get Wetter hypothesis, which emphasizes the role of sea surface temperature pattern change in driving regional tropical precipitation change. Future regional rainfall changes should thus be studied primarily in coupled ocean-atmosphere models.", - "Key Points", - " Regional tropical rainfall change is driven by surface warming patterns Land-sea warming contrasts can drive tropics-wide circulation change The direct CO2 effect is important for mean rainfall change, but not patterns" - ], + "abstract": "Mechanisms behind regional tropical rainfall responses to CO2 forcing are examined in idealized climate model experiments, traceable to transient forcing scenarios. As previously shown, the pattern of the first-year response of dynamical precipitation change to an abrupt CO2 increase is similar to the century-scale response. It is demonstrated here that this similarity is driven by surface temperature pattern change, not a direct atmospheric circulation response to CO2. This confirms the Warmer get Wetter hypothesis, which emphasizes the role of sea surface temperature pattern change in driving regional tropical precipitation change. Future regional rainfall changes should thus be studied primarily in coupled ocean-atmosphere models. ; ; Regional tropical rainfall change is driven by surface warming patterns Land-sea warming contrasts can drive tropics-wide circulation change The direct CO2 effect is important for mean rainfall change, but not patterns", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1902,11 +1867,7 @@ { "uri": "WOS:000332990500046", "title": "The dependence of transient climate sensitivity and radiative feedbacks on the spatial pattern of ocean heat uptake", - "abstract": [ - "The effect of ocean heat uptake (OHU) on transient global warming is studied in a multimodel framework. Simple heat sinks are prescribed in shallow aquaplanet ocean mixed layers underlying atmospheric general circulation models independently and combined with CO2 forcing. Sinks are localized to either tropical or high latitudes, representing distinct modes of OHU found in coupled simulations. Tropical OHU produces modest cooling at all latitudes, offsetting only a fraction of CO2 warming. High-latitude OHU produces three times more global mean cooling in a strongly polar-amplified pattern. Global sensitivities in each scenario are set primarily by large differences in local shortwave cloud feedbacks, robust across models. Differences in atmospheric energy transport set the pattern of temperature change. Results imply that global and regional warming rates depend sensitively on regional ocean processes setting the OHU pattern, and that equilibrium climate sensitivity cannot be reliably estimated from transient observations.", - "Key Points", - "Climate response depends strongly on spatial pattern of ocean heat uptake Different radiative feedbacks govern transient and equilibrium CO2 warming Results are robust across an ensemble of aquaplanet climate models" - ], + "abstract": "The effect of ocean heat uptake (OHU) on transient global warming is studied in a multimodel framework. Simple heat sinks are prescribed in shallow aquaplanet ocean mixed layers underlying atmospheric general circulation models independently and combined with CO2 forcing. Sinks are localized to either tropical or high latitudes, representing distinct modes of OHU found in coupled simulations. Tropical OHU produces modest cooling at all latitudes, offsetting only a fraction of CO2 warming. High-latitude OHU produces three times more global mean cooling in a strongly polar-amplified pattern. Global sensitivities in each scenario are set primarily by large differences in local shortwave cloud feedbacks, robust across models. Differences in atmospheric energy transport set the pattern of temperature change. Results imply that global and regional warming rates depend sensitively on regional ocean processes setting the OHU pattern, and that equilibrium climate sensitivity cannot be reliably estimated from transient observations. ; ; Climate response depends strongly on spatial pattern of ocean heat uptake Different radiative feedbacks govern transient and equilibrium CO2 warming Results are robust across an ensemble of aquaplanet climate models", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -2210,6 +2171,7 @@ { "uri": "WOS:000334908300017", "title": "A multimodel examination of climate extremes in an idealized geoengineering experiment", + "abstract": "", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -2274,6 +2236,7 @@ { "uri": "WOS:000334908300040", "title": "Ammonia emissions in the United States, European Union, and China derived by high-resolution inversion of ammonium wet deposition data: Interpretation with a new agricultural emissions inventory (MASAGE_NH3)", + "abstract": "", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ diff --git a/data/corpus-simple-rnsr-50.json b/data/corpus-simple-rnsr-50.json index 3ebd2b8..ad376d0 100644 --- a/data/corpus-simple-rnsr-50.json +++ b/data/corpus-simple-rnsr-50.json @@ -808,6 +808,7 @@ { "uri": "WOS:000334908300014", "title": "Comment on \"The added value to global model projections of climate change by dynamical downscaling: A case study over the continental U. S. using the GISS-ModelE2 and WRF models\" by Racherla et al.", + "abstract": "", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -835,6 +836,7 @@ { "uri": "WOS:000334908300031", "title": "The climatic effects of modifying cirrus clouds in a climate engineering framework", + "abstract": "", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -879,6 +881,7 @@ { "uri": "WOS:000334908300018", "title": "Postlaunch calibration and bias characterization of AMSU-A upper air sounding channels using GPS RO Data", + "abstract": "", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -1039,11 +1042,7 @@ { "uri": "WOS:000332995300006", "title": "Arctic sea ice and atmospheric circulation under the GeoMIP G1 scenario", - "abstract": [ - "We analyze simulated sea ice changes in eight different Earth System Models that have conducted experiment G1 of the Geoengineering Model Intercomparison Project (GeoMIP). The simulated response of balancing abrupt quadrupling of CO2 (abrupt4xCO2) with reduced shortwave radiation successfully moderates annually averaged Arctic temperature rise to about 1 degrees C, with modest changes in seasonal sea ice cycle compared with the preindustrial control simulations (piControl). Changes in summer and autumn sea ice extent are spatially correlated with temperature patterns but much less in winter and spring seasons. However, there are changes of 20% in sea ice concentration in all seasons, and these will induce changes in atmospheric circulation patterns. In summer and autumn, the models consistently simulate less sea ice relative to preindustrial simulations in the Beaufort, Chukchi, East Siberian, and Laptev Seas, and some models show increased sea ice in the Barents/Kara Seas region. Sea ice extent increases in the Greenland Sea, particularly in winter and spring and is to some extent associated with changed sea ice drift. Decreased sea ice cover in winter and spring in the Barents Sea is associated with increased cyclonic activity entering this area under G1. In comparison, the abrupt4xCO2 experiment shows almost total sea ice loss in September and strong correlation with regional temperatures in all seasons consistent with open ocean conditions. The tropospheric circulation displays a Pacific North America pattern-like anomaly with negative phase in G1-piControl and positive phase under abrupt4xCO2-piControl.", - "Key Points", - " Analysis of eight ESM focused on Arctic sea ice and feedback Response of Arctic to G1 geoengineering shows clear regional differences Sea ice is far different in detail under G1 than in pre industrial" - ], + "abstract": "We analyze simulated sea ice changes in eight different Earth System Models that have conducted experiment G1 of the Geoengineering Model Intercomparison Project (GeoMIP). The simulated response of balancing abrupt quadrupling of CO2 (abrupt4xCO2) with reduced shortwave radiation successfully moderates annually averaged Arctic temperature rise to about 1 degrees C, with modest changes in seasonal sea ice cycle compared with the preindustrial control simulations (piControl). Changes in summer and autumn sea ice extent are spatially correlated with temperature patterns but much less in winter and spring seasons. However, there are changes of 20% in sea ice concentration in all seasons, and these will induce changes in atmospheric circulation patterns. In summer and autumn, the models consistently simulate less sea ice relative to preindustrial simulations in the Beaufort, Chukchi, East Siberian, and Laptev Seas, and some models show increased sea ice in the Barents/Kara Seas region. Sea ice extent increases in the Greenland Sea, particularly in winter and spring and is to some extent associated with changed sea ice drift. Decreased sea ice cover in winter and spring in the Barents Sea is associated with increased cyclonic activity entering this area under G1. In comparison, the abrupt4xCO2 experiment shows almost total sea ice loss in September and strong correlation with regional temperatures in all seasons consistent with open ocean conditions. The tropospheric circulation displays a Pacific North America pattern-like anomaly with negative phase in G1-piControl and positive phase under abrupt4xCO2-piControl. ; ; Analysis of eight ESM focused on Arctic sea ice and feedback Response of Arctic to G1 geoengineering shows clear regional differences Sea ice is far different in detail under G1 than in pre industrial", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -1110,10 +1109,7 @@ { "uri": "WOS:000334264900040", "title": "Impact of the Atlanticmeridional overturning circulation on ocean heat storage and transient climate change", - "abstract": [ - "We propose here that the Atlantic meridional overturning circulation (AMOC) plays an important role in setting the effective heat capacity of the World Ocean and thus impacts the pace of transient climate change. The depth and strength of AMOC are shown to be strongly correlated with the depth of heat storage across a suite of state-of-the-art general circulation models (GCMs). In those models with a deeper and stronger AMOC, a smaller portion of the heat anomaly remains in the ocean mixed layer, and consequently, the surface temperature response is delayed. Representations of AMOC differ vastly across the GCMs, providing a major source of intermodel spread in the sea surface temperature (SST) response. A two-layer model fit to the GCMs is used to demonstrate that the intermodel spread in SSTs due to variations in the ocean's effective heat capacity is significant but smaller than the spread due to climate feedbacks.", - "Key Points AMOC plays a key role in setting the effective heat capacity of the World Ocean AMOC properties are correlated with depth of heat storage across CMIP5 GCMs Ocean heat storage is a major source of inter-GCM variability in SST response" - ], + "abstract": "We propose here that the Atlantic meridional overturning circulation (AMOC) plays an important role in setting the effective heat capacity of the World Ocean and thus impacts the pace of transient climate change. The depth and strength of AMOC are shown to be strongly correlated with the depth of heat storage across a suite of state-of-the-art general circulation models (GCMs). In those models with a deeper and stronger AMOC, a smaller portion of the heat anomaly remains in the ocean mixed layer, and consequently, the surface temperature response is delayed. Representations of AMOC differ vastly across the GCMs, providing a major source of intermodel spread in the sea surface temperature (SST) response. A two-layer model fit to the GCMs is used to demonstrate that the intermodel spread in SSTs due to variations in the ocean's effective heat capacity is significant but smaller than the spread due to climate feedbacks. ; AMOC plays a key role in setting the effective heat capacity of the World Ocean AMOC properties are correlated with depth of heat storage across CMIP5 GCMs Ocean heat storage is a major source of inter-GCM variability in SST response", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1145,11 +1141,7 @@ { "uri": "WOS:000334264900041", "title": "Astronomically forced variations in western African rainfall ( 21 N-20 S) during the Last Interglacial period", - "abstract": [ - "This study documents the long-term evolution of western African precipitation during the Last Interglacial (LIG). We compare geochemical records obtained on nine sediment cores from the western African margin to a transient simulation (130-115ka) performed with an ocean-atmosphere general circulation model and insolation as sole forcing. Good agreement between proxy records and model outputs indicates that long-term changes in western African precipitation largely responded to insolation variations during most of the LIG. After an early LIG dry phase (related to high-latitude iceberg melting or dating uncertainties), boreal summer insolation controlled the intensification of the North African monsoon between 127 and 122ka, perhaps facilitating human migrations out of Africa. Equatorial African rainfall slightly increased throughout the LIG in response to increasing annual insolation. East-west contrasting rainfall evolutions at 10-20 degrees S illustrate the complex southern African response, in contrast to more direct responses of North and equatorial western Africa, to insolation forcing.", - "Key Points", - "Insolation controls changes in western African rainfall during most of the LIG Early LIG meltwater may have delayed the North African monsoon intensification Complex response of southern African rainfall with east-west contrasting trends" - ], + "abstract": "This study documents the long-term evolution of western African precipitation during the Last Interglacial (LIG). We compare geochemical records obtained on nine sediment cores from the western African margin to a transient simulation (130-115ka) performed with an ocean-atmosphere general circulation model and insolation as sole forcing. Good agreement between proxy records and model outputs indicates that long-term changes in western African precipitation largely responded to insolation variations during most of the LIG. After an early LIG dry phase (related to high-latitude iceberg melting or dating uncertainties), boreal summer insolation controlled the intensification of the North African monsoon between 127 and 122ka, perhaps facilitating human migrations out of Africa. Equatorial African rainfall slightly increased throughout the LIG in response to increasing annual insolation. East-west contrasting rainfall evolutions at 10-20 degrees S illustrate the complex southern African response, in contrast to more direct responses of North and equatorial western Africa, to insolation forcing. ; ; Insolation controls changes in western African rainfall during most of the LIG Early LIG meltwater may have delayed the North African monsoon intensification Complex response of southern African rainfall with east-west contrasting trends", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1239,11 +1231,7 @@ { "uri": "WOS:000333578800056", "title": "Predictability of the quasi-biennial oscillation and its northern winter teleconnection on seasonal to decadal timescales", - "abstract": [ - "The predictability of the quasi-biennial oscillation (QBO) is examined in initialized climate forecasts extending out to lead times of years. We use initialized retrospective predictions made with coupled ocean-atmosphere climate models that have an internally generated QBO. We demonstrate predictability of the QBO extending more than 3 years into the future, well beyond timescales normally associated with internal atmospheric processes. Correlation scores with observational analyses exceed 0.7 at a lead time of 12months. We also examine the variation of predictability with season and QBO phase and find that skill is lowest in winter. An assessment of perfect predictability suggests that higher skill may be achievable through improved initialization and climate modeling of the QBO, although this may depend on the realism of gravity wave source parameterizations in the models. Finally, we show that skilful prediction of the QBO itself does not guarantee predictability of the extratropical winter teleconnection that is important for surface winter climate prediction.", - "Key Points", - " The QBO is skilfully predicted in seasonal-decadal forecast systems Further improvements in predictions of the QBO are possible The QBO winter surface teleconnection is reproduced with mixed success" - ], + "abstract": "The predictability of the quasi-biennial oscillation (QBO) is examined in initialized climate forecasts extending out to lead times of years. We use initialized retrospective predictions made with coupled ocean-atmosphere climate models that have an internally generated QBO. We demonstrate predictability of the QBO extending more than 3 years into the future, well beyond timescales normally associated with internal atmospheric processes. Correlation scores with observational analyses exceed 0.7 at a lead time of 12months. We also examine the variation of predictability with season and QBO phase and find that skill is lowest in winter. An assessment of perfect predictability suggests that higher skill may be achievable through improved initialization and climate modeling of the QBO, although this may depend on the realism of gravity wave source parameterizations in the models. Finally, we show that skilful prediction of the QBO itself does not guarantee predictability of the extratropical winter teleconnection that is important for surface winter climate prediction. ; ; The QBO is skilfully predicted in seasonal-decadal forecast systems Further improvements in predictions of the QBO are possible The QBO winter surface teleconnection is reproduced with mixed success", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1290,11 +1278,7 @@ { "uri": "WOS:000333578800054", "title": "Modifications of the quasi-biennial oscillation by a geoengineering perturbation of the stratospheric aerosol layer", - "abstract": [ - "This paper examines the impact of geoengineering via stratospheric sulfate aerosol on the quasi-biennial oscillation (QBO) using the NASA Goddard Earth Observing System version 5 Chemistry Climate Model. We performed four 30 year simulations with a continuous injection of sulfur dioxide on the equator at 0 degrees longitude. The four simulations differ by the amount of sulfur dioxide injected (5 Tg/yr and 2.5 Tg/yr) and the altitude of the injection (16km-25km and 22km-25km). We find that such an injection dramatically alters the quasi-biennial oscillation, prolonging the phase of easterly shear with respect to the control simulation. This is caused by the increased aerosol heating and associated warming in the tropical lower stratosphere and higher residual vertical velocity. In the case of maximum perturbation, i.e., highest stratospheric aerosol burden, the lower tropical stratosphere is locked into a permanent westerly QBO phase.", - "Key Points", - " Geoengineering aerosol would prolong the westerly phase of the QBO Large geoengineering stratospheric aerosol injections might interrupt the QBO QBO changes are due to aerosol warming and increased residual vertical velocity" - ], + "abstract": "This paper examines the impact of geoengineering via stratospheric sulfate aerosol on the quasi-biennial oscillation (QBO) using the NASA Goddard Earth Observing System version 5 Chemistry Climate Model. We performed four 30 year simulations with a continuous injection of sulfur dioxide on the equator at 0 degrees longitude. The four simulations differ by the amount of sulfur dioxide injected (5 Tg/yr and 2.5 Tg/yr) and the altitude of the injection (16km-25km and 22km-25km). We find that such an injection dramatically alters the quasi-biennial oscillation, prolonging the phase of easterly shear with respect to the control simulation. This is caused by the increased aerosol heating and associated warming in the tropical lower stratosphere and higher residual vertical velocity. In the case of maximum perturbation, i.e., highest stratospheric aerosol burden, the lower tropical stratosphere is locked into a permanent westerly QBO phase. ; ; Geoengineering aerosol would prolong the westerly phase of the QBO Large geoengineering stratospheric aerosol injections might interrupt the QBO QBO changes are due to aerosol warming and increased residual vertical velocity", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1335,11 +1319,7 @@ { "uri": "WOS:000333578800044", "title": "The implication of radiative forcing and feedback for meridional energy transport", - "abstract": [ - "The distributions of radiative forcing and feedback in the Coupled Model Intercomparison Project phase 5 abrupt4xCO2 and Historical experiments are diagnosed, with a focus on their effects on the zonal mean structure of the top-of-the-atmosphere radiation anomalies and implications for the meridional energy transport. It is found that because the greenhouse gas longwave forcing peaks in the low latitudes, it reinforces the equator-to-pole net radiation gradient and accounts for the increase in the poleward energy transport in both hemispheres under global warming. The shortwave forcing by aerosol, ozone, etc. peaks in the Northern Hemisphere and instead implies an interhemispheric energy transport. Although the water vapor feedback also reinforces the equator-to-pole gradient of the net radiation, the temperature and albedo feedback act against it. The feedback tend to offset the zonal mean radiation anomaly caused by the forcing, although the overall feedback effect on the energy transport is rather uncertain, mainly due to the uncertainty in the cloud feedback.", - "Key Points", - " CO2 forcing increases meridional gradient in net radiation Forcing, rather than feedback, accounts for enhanced poleward energy transport Aerosol forcing accounts for an inter-hemispheric transport anomaly" - ], + "abstract": "The distributions of radiative forcing and feedback in the Coupled Model Intercomparison Project phase 5 abrupt4xCO2 and Historical experiments are diagnosed, with a focus on their effects on the zonal mean structure of the top-of-the-atmosphere radiation anomalies and implications for the meridional energy transport. It is found that because the greenhouse gas longwave forcing peaks in the low latitudes, it reinforces the equator-to-pole net radiation gradient and accounts for the increase in the poleward energy transport in both hemispheres under global warming. The shortwave forcing by aerosol, ozone, etc. peaks in the Northern Hemisphere and instead implies an interhemispheric energy transport. Although the water vapor feedback also reinforces the equator-to-pole gradient of the net radiation, the temperature and albedo feedback act against it. The feedback tend to offset the zonal mean radiation anomaly caused by the forcing, although the overall feedback effect on the energy transport is rather uncertain, mainly due to the uncertainty in the cloud feedback. ; ; CO2 forcing increases meridional gradient in net radiation Forcing, rather than feedback, accounts for enhanced poleward energy transport Aerosol forcing accounts for an inter-hemispheric transport anomaly", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1374,11 +1354,7 @@ { "uri": "WOS:000332995300011", "title": "Evaluation of interpolation techniques for the creation of gridded daily precipitation ( 1 x 1 km2); Cyprus, 1980-2010", - "abstract": [ - "High-resolution gridded daily data sets are essential for natural resource management and the analyses of climate changes and their effects. This study aims to evaluate the performance of 15 simple or complex interpolation techniques in reproducing daily precipitation at a resolution of 1km(2) over topographically complex areas. Methods are tested considering two different sets of observation densities and different rainfall amounts. We used rainfall data that were recorded at 74 and 145 observational stations, respectively, spread over the 5760km(2) of the Republic of Cyprus, in the Eastern Mediterranean. Regression analyses utilizing geographical copredictors and neighboring interpolation techniques were evaluated both in isolation and combined. Linear multiple regression (LMR) and geographically weighted regression methods (GWR) were tested. These included a step-wise selection of covariables, as well as inverse distance weighting (IDW), kriging, and 3D-thin plate splines (TPS). The relative rank of the different techniques changes with different station density and rainfall amounts. Our results indicate that TPS performs well for low station density and large-scale events and also when coupled with regression models. It performs poorly for high station density. The opposite is observed when using IDW. Simple IDW performs best for local events, while a combination of step-wise GWR and IDW proves to be the best method for large-scale events and high station density. This study indicates that the use of step-wise regression with a variable set of geographic parameters can improve the interpolation of large-scale events because it facilitates the representation of local climate dynamics.", - "Key Points", - " Interpolation of daily rainfall data using 15 spatial interpolation methods Relative skill of interpolation techniques depends on observation density High and low rainfall events should be treated with different techniques" - ], + "abstract": "High-resolution gridded daily data sets are essential for natural resource management and the analyses of climate changes and their effects. This study aims to evaluate the performance of 15 simple or complex interpolation techniques in reproducing daily precipitation at a resolution of 1km(2) over topographically complex areas. Methods are tested considering two different sets of observation densities and different rainfall amounts. We used rainfall data that were recorded at 74 and 145 observational stations, respectively, spread over the 5760km(2) of the Republic of Cyprus, in the Eastern Mediterranean. Regression analyses utilizing geographical copredictors and neighboring interpolation techniques were evaluated both in isolation and combined. Linear multiple regression (LMR) and geographically weighted regression methods (GWR) were tested. These included a step-wise selection of covariables, as well as inverse distance weighting (IDW), kriging, and 3D-thin plate splines (TPS). The relative rank of the different techniques changes with different station density and rainfall amounts. Our results indicate that TPS performs well for low station density and large-scale events and also when coupled with regression models. It performs poorly for high station density. The opposite is observed when using IDW. Simple IDW performs best for local events, while a combination of step-wise GWR and IDW proves to be the best method for large-scale events and high station density. This study indicates that the use of step-wise regression with a variable set of geographic parameters can improve the interpolation of large-scale events because it facilitates the representation of local climate dynamics. ; ; Interpolation of daily rainfall data using 15 spatial interpolation methods Relative skill of interpolation techniques depends on observation density High and low rainfall events should be treated with different techniques", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -1474,10 +1450,7 @@ { "uri": "WOS:000333885700023", "title": "Cirrus cloud susceptibility to the injection of ice nuclei in the upper troposphere", - "abstract": [ - "Due to their net warming effect, cirrus clouds play a crucial role in the climate system. A recently proposed climate engineering mechanism (CEM) intends to reduce high cloud cover by seeding cirrus clouds with efficient ice nuclei (IN) and therefore cool climate. Here, the susceptibility of cirrus clouds to the injection of ice nuclei in the upper troposphere is investigated in the extended Community Atmospheric Model version 5 (CAM5). Due to large uncertainties associated with the dominant ice nucleation mechanism in cirrus clouds, different control cases were simulated. In addition to pure homogeneous and heterogeneous nucleation, cases with competition between homogeneous and heterogeneous nucleation and different fractions of mineral dust active as IN were considered. Whereas seeding in the pure heterogeneous case leads to a strong warming due to overseeding, an optimal seeding IN concentration of approximately 18 l(-1) was found for the other cases. For the optimal seeding concentration, a reduction in the net cloud forcing (NCF) of up to 2 W m(-2) was simulated, corresponding to a strong cooling effect. To optimize the cooling and minimize the amount of seeding material, globally nonuniform seeding strategies were tested, with minimal seeding in the summer hemisphere and in the tropics. With seeding applied to less than half the globe, an even stronger reduction in the NCF was achieved. This suggests that the CEM could work for an atmosphere even with considerable heterogeneous ice nucleation and that the desired cooling could be obtained without seeding the entire globe.", - "Key Points Cirrus cloud seeding in the upper troposphere was simulated in CAM5 Both cirrus cloud susceptibility and short-term climate response were analyzed Even globally non-uniform injection of IN leads to the desired cooling" - ], + "abstract": "Due to their net warming effect, cirrus clouds play a crucial role in the climate system. A recently proposed climate engineering mechanism (CEM) intends to reduce high cloud cover by seeding cirrus clouds with efficient ice nuclei (IN) and therefore cool climate. Here, the susceptibility of cirrus clouds to the injection of ice nuclei in the upper troposphere is investigated in the extended Community Atmospheric Model version 5 (CAM5). Due to large uncertainties associated with the dominant ice nucleation mechanism in cirrus clouds, different control cases were simulated. In addition to pure homogeneous and heterogeneous nucleation, cases with competition between homogeneous and heterogeneous nucleation and different fractions of mineral dust active as IN were considered. Whereas seeding in the pure heterogeneous case leads to a strong warming due to overseeding, an optimal seeding IN concentration of approximately 18 l(-1) was found for the other cases. For the optimal seeding concentration, a reduction in the net cloud forcing (NCF) of up to 2 W m(-2) was simulated, corresponding to a strong cooling effect. To optimize the cooling and minimize the amount of seeding material, globally nonuniform seeding strategies were tested, with minimal seeding in the summer hemisphere and in the tropics. With seeding applied to less than half the globe, an even stronger reduction in the NCF was achieved. This suggests that the CEM could work for an atmosphere even with considerable heterogeneous ice nucleation and that the desired cooling could be obtained without seeding the entire globe. ; Cirrus cloud seeding in the upper troposphere was simulated in CAM5 Both cirrus cloud susceptibility and short-term climate response were analyzed Even globally non-uniform injection of IN leads to the desired cooling", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -1518,11 +1491,7 @@ { "uri": "WOS:000333885700020", "title": "What controls the interannual variation of the wet season onsets over the Amazon?", - "abstract": [ - "Previous studies have established that sea surface temperature anomalies (SSTAs) in the tropical Pacific and Atlantic are the main forcing of the interannual variation of the wet season onsets in the Amazon. However, this variation appears to be complex and not uniquely determined by SSTAs. What causes such a complexity and to what extent the interannual variation of the wet season onsets is predictable remain unclear. This study suggests that such a complex relationship is the result of several competing processes, which are nonlinearly related to the SSTAs. In particular, three dry season conditions are crucial for determining interannual variation of the wet season onset. (i) A poleward shift of the Southern Hemisphere subtropical jet (SHSJ) over the South American sector, initiated from a wave train-like structure possibly forced by south central Pacific SST patterns, can prevent cold frontal systems from moving northward into the Amazon. This delays cold air incursion and results in late wet season onset over the southern Amazon. (ii) An anomalous anticyclonic center, which enhances westerly wind at 850hPa over the southern Amazon and also the South American low-level jets, leads to moisture export from the southern Amazon to La Plata basin and reduces convective systems that provide elevated diabatic heating. (iii) Smaller convective available potential energy (CAPE) limits local thermodynamically driven convection. Based on the stepwise and partial least squares regressions, these three selected preseasonal conditions (Nino 4, SHSJ, and CAPE) can explain 57% of the total variance of the wet season onset.", - "Key Points", - " The wet season onset over the Amazon is not uniquely deterimined by SSTAs A poleward SHSJ, enhanced U850, and lower CAPE are crucial for delayed onset Selected conditions can explain 57% of the total variance" - ], + "abstract": "Previous studies have established that sea surface temperature anomalies (SSTAs) in the tropical Pacific and Atlantic are the main forcing of the interannual variation of the wet season onsets in the Amazon. However, this variation appears to be complex and not uniquely determined by SSTAs. What causes such a complexity and to what extent the interannual variation of the wet season onsets is predictable remain unclear. This study suggests that such a complex relationship is the result of several competing processes, which are nonlinearly related to the SSTAs. In particular, three dry season conditions are crucial for determining interannual variation of the wet season onset. (i) A poleward shift of the Southern Hemisphere subtropical jet (SHSJ) over the South American sector, initiated from a wave train-like structure possibly forced by south central Pacific SST patterns, can prevent cold frontal systems from moving northward into the Amazon. This delays cold air incursion and results in late wet season onset over the southern Amazon. (ii) An anomalous anticyclonic center, which enhances westerly wind at 850hPa over the southern Amazon and also the South American low-level jets, leads to moisture export from the southern Amazon to La Plata basin and reduces convective systems that provide elevated diabatic heating. (iii) Smaller convective available potential energy (CAPE) limits local thermodynamically driven convection. Based on the stepwise and partial least squares regressions, these three selected preseasonal conditions (Nino 4, SHSJ, and CAPE) can explain 57% of the total variance of the wet season onset. ; ; The wet season onset over the Amazon is not uniquely deterimined by SSTAs A poleward SHSJ, enhanced U850, and lower CAPE are crucial for delayed onset Selected conditions can explain 57% of the total variance", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -1710,11 +1679,7 @@ { "uri": "WOS:000332991000059", "title": "Surface warming patterns drive tropical rainfall pattern responses to CO2 forcing on all timescales", - "abstract": [ - "Mechanisms behind regional tropical rainfall responses to CO2 forcing are examined in idealized climate model experiments, traceable to transient forcing scenarios. As previously shown, the pattern of the first-year response of dynamical precipitation change to an abrupt CO2 increase is similar to the century-scale response. It is demonstrated here that this similarity is driven by surface temperature pattern change, not a direct atmospheric circulation response to CO2. This confirms the Warmer get Wetter hypothesis, which emphasizes the role of sea surface temperature pattern change in driving regional tropical precipitation change. Future regional rainfall changes should thus be studied primarily in coupled ocean-atmosphere models.", - "Key Points", - " Regional tropical rainfall change is driven by surface warming patterns Land-sea warming contrasts can drive tropics-wide circulation change The direct CO2 effect is important for mean rainfall change, but not patterns" - ], + "abstract": "Mechanisms behind regional tropical rainfall responses to CO2 forcing are examined in idealized climate model experiments, traceable to transient forcing scenarios. As previously shown, the pattern of the first-year response of dynamical precipitation change to an abrupt CO2 increase is similar to the century-scale response. It is demonstrated here that this similarity is driven by surface temperature pattern change, not a direct atmospheric circulation response to CO2. This confirms the Warmer get Wetter hypothesis, which emphasizes the role of sea surface temperature pattern change in driving regional tropical precipitation change. Future regional rainfall changes should thus be studied primarily in coupled ocean-atmosphere models. ; ; Regional tropical rainfall change is driven by surface warming patterns Land-sea warming contrasts can drive tropics-wide circulation change The direct CO2 effect is important for mean rainfall change, but not patterns", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1782,11 +1747,7 @@ { "uri": "WOS:000332990500046", "title": "The dependence of transient climate sensitivity and radiative feedbacks on the spatial pattern of ocean heat uptake", - "abstract": [ - "The effect of ocean heat uptake (OHU) on transient global warming is studied in a multimodel framework. Simple heat sinks are prescribed in shallow aquaplanet ocean mixed layers underlying atmospheric general circulation models independently and combined with CO2 forcing. Sinks are localized to either tropical or high latitudes, representing distinct modes of OHU found in coupled simulations. Tropical OHU produces modest cooling at all latitudes, offsetting only a fraction of CO2 warming. High-latitude OHU produces three times more global mean cooling in a strongly polar-amplified pattern. Global sensitivities in each scenario are set primarily by large differences in local shortwave cloud feedbacks, robust across models. Differences in atmospheric energy transport set the pattern of temperature change. Results imply that global and regional warming rates depend sensitively on regional ocean processes setting the OHU pattern, and that equilibrium climate sensitivity cannot be reliably estimated from transient observations.", - "Key Points", - "Climate response depends strongly on spatial pattern of ocean heat uptake Different radiative feedbacks govern transient and equilibrium CO2 warming Results are robust across an ensemble of aquaplanet climate models" - ], + "abstract": "The effect of ocean heat uptake (OHU) on transient global warming is studied in a multimodel framework. Simple heat sinks are prescribed in shallow aquaplanet ocean mixed layers underlying atmospheric general circulation models independently and combined with CO2 forcing. Sinks are localized to either tropical or high latitudes, representing distinct modes of OHU found in coupled simulations. Tropical OHU produces modest cooling at all latitudes, offsetting only a fraction of CO2 warming. High-latitude OHU produces three times more global mean cooling in a strongly polar-amplified pattern. Global sensitivities in each scenario are set primarily by large differences in local shortwave cloud feedbacks, robust across models. Differences in atmospheric energy transport set the pattern of temperature change. Results imply that global and regional warming rates depend sensitively on regional ocean processes setting the OHU pattern, and that equilibrium climate sensitivity cannot be reliably estimated from transient observations. ; ; Climate response depends strongly on spatial pattern of ocean heat uptake Different radiative feedbacks govern transient and equilibrium CO2 warming Results are robust across an ensemble of aquaplanet climate models", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -2067,6 +2028,7 @@ { "uri": "WOS:000334908300017", "title": "A multimodel examination of climate extremes in an idealized geoengineering experiment", + "abstract": "", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -2128,6 +2090,7 @@ { "uri": "WOS:000334908300040", "title": "Ammonia emissions in the United States, European Union, and China derived by high-resolution inversion of ammonium wet deposition data: Interpretation with a new agricultural emissions inventory (MASAGE_NH3)", + "abstract": "", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ diff --git a/data/corpus-simple-teeft-en-50.json b/data/corpus-simple-teeft-en-50.json index 364ce70..6a38bcf 100644 --- a/data/corpus-simple-teeft-en-50.json +++ b/data/corpus-simple-teeft-en-50.json @@ -496,18 +496,7 @@ "etab": [], "rnsr_id": [], "instituts": [], - "teeft": [ - "katabatic", - "katabatic winds", - "vertical levels", - "high resolution", - "low resolution", - "surface winds", - "key components", - "antarctica's harsh climate", - "renowned katabatic winds", - "fiercest surface winds" - ] + "teeft": "One of the key components of Antarctica's harsh climate is its renowned katabatic winds, which are among the fiercest surface winds on Earth. Caused primarily by strong surface cooling over the sloping ice surface, these semipermanent winds result primarily from the strong surface temperature inversion and associated temperature deficit between the surface layer and the free atmosphere aloft. Katabatic winds exert a strong effect on the mass budget of the Antarctic ice sheet by affecting snowdrift (sublimation) and by (partially) regulating the net atmospheric moisture transports toward the Antarctic. It has been suggested that greenhouse warming may lead to reduced surface cooling and weakened katabatic winds. This is tested by using a global climate model (EC-Earth) in prescribed sea surface temperature simulations of the present-day (2002-2006) and future (2094-2098) climates. Because simulated topographically induced katabatic winds are likely to depend on the model grid, we employ two model resolutions: (1) T159L62 (similar to 100 km, 62 vertical levels) and (2) T799L91 (similar to 20 km, 91 vertical levels). It is shown here that present-day surface winds over Antarctica in high resolution are generally stronger than in low resolution, especially in the escarpment region with its steep orography. Simulated surface winds are generally underestimated with respect to observations, in particular the strongest winds (occurring over steep slopes), and especially in low resolution. The seasonal cycle in surface winds is simulated fairly accurately. Surface temperatures are also relatively well simulated (when corrected for elevation differences), especially in high resolution." } }, { @@ -1078,6 +1067,7 @@ { "uri": "WOS:000334908300014", "title": "Comment on \"The added value to global model projections of climate change by dynamical downscaling: A case study over the continental U. S. using the GISS-ModelE2 and WRF models\" by Racherla et al.", + "abstract": "", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -1109,6 +1099,7 @@ { "uri": "WOS:000334908300031", "title": "The climatic effects of modifying cirrus clouds in a climate engineering framework", + "abstract": "", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -1157,6 +1148,7 @@ { "uri": "WOS:000334908300018", "title": "Postlaunch calibration and bias characterization of AMSU-A upper air sounding channels using GPS RO Data", + "abstract": "", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -1366,11 +1358,7 @@ { "uri": "WOS:000332995300006", "title": "Arctic sea ice and atmospheric circulation under the GeoMIP G1 scenario", - "abstract": [ - "We analyze simulated sea ice changes in eight different Earth System Models that have conducted experiment G1 of the Geoengineering Model Intercomparison Project (GeoMIP). The simulated response of balancing abrupt quadrupling of CO2 (abrupt4xCO2) with reduced shortwave radiation successfully moderates annually averaged Arctic temperature rise to about 1 degrees C, with modest changes in seasonal sea ice cycle compared with the preindustrial control simulations (piControl). Changes in summer and autumn sea ice extent are spatially correlated with temperature patterns but much less in winter and spring seasons. However, there are changes of 20% in sea ice concentration in all seasons, and these will induce changes in atmospheric circulation patterns. In summer and autumn, the models consistently simulate less sea ice relative to preindustrial simulations in the Beaufort, Chukchi, East Siberian, and Laptev Seas, and some models show increased sea ice in the Barents/Kara Seas region. Sea ice extent increases in the Greenland Sea, particularly in winter and spring and is to some extent associated with changed sea ice drift. Decreased sea ice cover in winter and spring in the Barents Sea is associated with increased cyclonic activity entering this area under G1. In comparison, the abrupt4xCO2 experiment shows almost total sea ice loss in September and strong correlation with regional temperatures in all seasons consistent with open ocean conditions. The tropospheric circulation displays a Pacific North America pattern-like anomaly with negative phase in G1-piControl and positive phase under abrupt4xCO2-piControl.", - "Key Points", - " Analysis of eight ESM focused on Arctic sea ice and feedback Response of Arctic to G1 geoengineering shows clear regional differences Sea ice is far different in detail under G1 than in pre industrial" - ], + "abstract": "We analyze simulated sea ice changes in eight different Earth System Models that have conducted experiment G1 of the Geoengineering Model Intercomparison Project (GeoMIP). The simulated response of balancing abrupt quadrupling of CO2 (abrupt4xCO2) with reduced shortwave radiation successfully moderates annually averaged Arctic temperature rise to about 1 degrees C, with modest changes in seasonal sea ice cycle compared with the preindustrial control simulations (piControl). Changes in summer and autumn sea ice extent are spatially correlated with temperature patterns but much less in winter and spring seasons. However, there are changes of 20% in sea ice concentration in all seasons, and these will induce changes in atmospheric circulation patterns. In summer and autumn, the models consistently simulate less sea ice relative to preindustrial simulations in the Beaufort, Chukchi, East Siberian, and Laptev Seas, and some models show increased sea ice in the Barents/Kara Seas region. Sea ice extent increases in the Greenland Sea, particularly in winter and spring and is to some extent associated with changed sea ice drift. Decreased sea ice cover in winter and spring in the Barents Sea is associated with increased cyclonic activity entering this area under G1. In comparison, the abrupt4xCO2 experiment shows almost total sea ice loss in September and strong correlation with regional temperatures in all seasons consistent with open ocean conditions. The tropospheric circulation displays a Pacific North America pattern-like anomaly with negative phase in G1-piControl and positive phase under abrupt4xCO2-piControl. ; ; Analysis of eight ESM focused on Arctic sea ice and feedback Response of Arctic to G1 geoengineering shows clear regional differences Sea ice is far different in detail under G1 than in pre industrial", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -1452,10 +1440,7 @@ { "uri": "WOS:000334264900040", "title": "Impact of the Atlanticmeridional overturning circulation on ocean heat storage and transient climate change", - "abstract": [ - "We propose here that the Atlantic meridional overturning circulation (AMOC) plays an important role in setting the effective heat capacity of the World Ocean and thus impacts the pace of transient climate change. The depth and strength of AMOC are shown to be strongly correlated with the depth of heat storage across a suite of state-of-the-art general circulation models (GCMs). In those models with a deeper and stronger AMOC, a smaller portion of the heat anomaly remains in the ocean mixed layer, and consequently, the surface temperature response is delayed. Representations of AMOC differ vastly across the GCMs, providing a major source of intermodel spread in the sea surface temperature (SST) response. A two-layer model fit to the GCMs is used to demonstrate that the intermodel spread in SSTs due to variations in the ocean's effective heat capacity is significant but smaller than the spread due to climate feedbacks.", - "Key Points AMOC plays a key role in setting the effective heat capacity of the World Ocean AMOC properties are correlated with depth of heat storage across CMIP5 GCMs Ocean heat storage is a major source of inter-GCM variability in SST response" - ], + "abstract": "We propose here that the Atlantic meridional overturning circulation (AMOC) plays an important role in setting the effective heat capacity of the World Ocean and thus impacts the pace of transient climate change. The depth and strength of AMOC are shown to be strongly correlated with the depth of heat storage across a suite of state-of-the-art general circulation models (GCMs). In those models with a deeper and stronger AMOC, a smaller portion of the heat anomaly remains in the ocean mixed layer, and consequently, the surface temperature response is delayed. Representations of AMOC differ vastly across the GCMs, providing a major source of intermodel spread in the sea surface temperature (SST) response. A two-layer model fit to the GCMs is used to demonstrate that the intermodel spread in SSTs due to variations in the ocean's effective heat capacity is significant but smaller than the spread due to climate feedbacks. ; AMOC plays a key role in setting the effective heat capacity of the World Ocean AMOC properties are correlated with depth of heat storage across CMIP5 GCMs Ocean heat storage is a major source of inter-GCM variability in SST response", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1488,25 +1473,21 @@ "teeft": [ "amoc", "gcms", + "effective heat capacity", + "heat storage", + "major source", "intermodel spread", "atlantic meridional", "circulation amoc", "important role", - "effective heat capacity", - "world ocean", - "transient climate change", - "heat storage" + "world ocean" ] } }, { "uri": "WOS:000334264900041", "title": "Astronomically forced variations in western African rainfall ( 21 N-20 S) during the Last Interglacial period", - "abstract": [ - "This study documents the long-term evolution of western African precipitation during the Last Interglacial (LIG). We compare geochemical records obtained on nine sediment cores from the western African margin to a transient simulation (130-115ka) performed with an ocean-atmosphere general circulation model and insolation as sole forcing. Good agreement between proxy records and model outputs indicates that long-term changes in western African precipitation largely responded to insolation variations during most of the LIG. After an early LIG dry phase (related to high-latitude iceberg melting or dating uncertainties), boreal summer insolation controlled the intensification of the North African monsoon between 127 and 122ka, perhaps facilitating human migrations out of Africa. Equatorial African rainfall slightly increased throughout the LIG in response to increasing annual insolation. East-west contrasting rainfall evolutions at 10-20 degrees S illustrate the complex southern African response, in contrast to more direct responses of North and equatorial western Africa, to insolation forcing.", - "Key Points", - "Insolation controls changes in western African rainfall during most of the LIG Early LIG meltwater may have delayed the North African monsoon intensification Complex response of southern African rainfall with east-west contrasting trends" - ], + "abstract": "This study documents the long-term evolution of western African precipitation during the Last Interglacial (LIG). We compare geochemical records obtained on nine sediment cores from the western African margin to a transient simulation (130-115ka) performed with an ocean-atmosphere general circulation model and insolation as sole forcing. Good agreement between proxy records and model outputs indicates that long-term changes in western African precipitation largely responded to insolation variations during most of the LIG. After an early LIG dry phase (related to high-latitude iceberg melting or dating uncertainties), boreal summer insolation controlled the intensification of the North African monsoon between 127 and 122ka, perhaps facilitating human migrations out of Africa. Equatorial African rainfall slightly increased throughout the LIG in response to increasing annual insolation. East-west contrasting rainfall evolutions at 10-20 degrees S illustrate the complex southern African response, in contrast to more direct responses of North and equatorial western Africa, to insolation forcing. ; ; Insolation controls changes in western African rainfall during most of the LIG Early LIG meltwater may have delayed the North African monsoon intensification Complex response of southern African rainfall with east-west contrasting trends", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1545,8 +1526,8 @@ "rnsr_id": [], "instituts": [], "teeft": [ - "insolation", "lig", + "insolation", "western african precipitation", "study documents", "long-term evolution", @@ -1626,11 +1607,7 @@ { "uri": "WOS:000333578800056", "title": "Predictability of the quasi-biennial oscillation and its northern winter teleconnection on seasonal to decadal timescales", - "abstract": [ - "The predictability of the quasi-biennial oscillation (QBO) is examined in initialized climate forecasts extending out to lead times of years. We use initialized retrospective predictions made with coupled ocean-atmosphere climate models that have an internally generated QBO. We demonstrate predictability of the QBO extending more than 3 years into the future, well beyond timescales normally associated with internal atmospheric processes. Correlation scores with observational analyses exceed 0.7 at a lead time of 12months. We also examine the variation of predictability with season and QBO phase and find that skill is lowest in winter. An assessment of perfect predictability suggests that higher skill may be achievable through improved initialization and climate modeling of the QBO, although this may depend on the realism of gravity wave source parameterizations in the models. Finally, we show that skilful prediction of the QBO itself does not guarantee predictability of the extratropical winter teleconnection that is important for surface winter climate prediction.", - "Key Points", - " The QBO is skilfully predicted in seasonal-decadal forecast systems Further improvements in predictions of the QBO are possible The QBO winter surface teleconnection is reproduced with mixed success" - ], + "abstract": "The predictability of the quasi-biennial oscillation (QBO) is examined in initialized climate forecasts extending out to lead times of years. We use initialized retrospective predictions made with coupled ocean-atmosphere climate models that have an internally generated QBO. We demonstrate predictability of the QBO extending more than 3 years into the future, well beyond timescales normally associated with internal atmospheric processes. Correlation scores with observational analyses exceed 0.7 at a lead time of 12months. We also examine the variation of predictability with season and QBO phase and find that skill is lowest in winter. An assessment of perfect predictability suggests that higher skill may be achievable through improved initialization and climate modeling of the QBO, although this may depend on the realism of gravity wave source parameterizations in the models. Finally, we show that skilful prediction of the QBO itself does not guarantee predictability of the extratropical winter teleconnection that is important for surface winter climate prediction. ; ; The QBO is skilfully predicted in seasonal-decadal forecast systems Further improvements in predictions of the QBO are possible The QBO winter surface teleconnection is reproduced with mixed success", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1692,11 +1669,7 @@ { "uri": "WOS:000333578800054", "title": "Modifications of the quasi-biennial oscillation by a geoengineering perturbation of the stratospheric aerosol layer", - "abstract": [ - "This paper examines the impact of geoengineering via stratospheric sulfate aerosol on the quasi-biennial oscillation (QBO) using the NASA Goddard Earth Observing System version 5 Chemistry Climate Model. We performed four 30 year simulations with a continuous injection of sulfur dioxide on the equator at 0 degrees longitude. The four simulations differ by the amount of sulfur dioxide injected (5 Tg/yr and 2.5 Tg/yr) and the altitude of the injection (16km-25km and 22km-25km). We find that such an injection dramatically alters the quasi-biennial oscillation, prolonging the phase of easterly shear with respect to the control simulation. This is caused by the increased aerosol heating and associated warming in the tropical lower stratosphere and higher residual vertical velocity. In the case of maximum perturbation, i.e., highest stratospheric aerosol burden, the lower tropical stratosphere is locked into a permanent westerly QBO phase.", - "Key Points", - " Geoengineering aerosol would prolong the westerly phase of the QBO Large geoengineering stratospheric aerosol injections might interrupt the QBO QBO changes are due to aerosol warming and increased residual vertical velocity" - ], + "abstract": "This paper examines the impact of geoengineering via stratospheric sulfate aerosol on the quasi-biennial oscillation (QBO) using the NASA Goddard Earth Observing System version 5 Chemistry Climate Model. We performed four 30 year simulations with a continuous injection of sulfur dioxide on the equator at 0 degrees longitude. The four simulations differ by the amount of sulfur dioxide injected (5 Tg/yr and 2.5 Tg/yr) and the altitude of the injection (16km-25km and 22km-25km). We find that such an injection dramatically alters the quasi-biennial oscillation, prolonging the phase of easterly shear with respect to the control simulation. This is caused by the increased aerosol heating and associated warming in the tropical lower stratosphere and higher residual vertical velocity. In the case of maximum perturbation, i.e., highest stratospheric aerosol burden, the lower tropical stratosphere is locked into a permanent westerly QBO phase. ; ; Geoengineering aerosol would prolong the westerly phase of the QBO Large geoengineering stratospheric aerosol injections might interrupt the QBO QBO changes are due to aerosol warming and increased residual vertical velocity", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1736,6 +1709,8 @@ "rnsr_id": [], "instituts": [], "teeft": [ + "qbo", + "stratospheric", "sulfur dioxide", "tg yr", "stratospheric sulfate aerosol", @@ -1743,20 +1718,14 @@ "nasa goddard earth", "system version", "chemistry climate model", - "year simulations", - "continuous injection", - "degrees longitude" + "year simulations" ] } }, { "uri": "WOS:000333578800044", "title": "The implication of radiative forcing and feedback for meridional energy transport", - "abstract": [ - "The distributions of radiative forcing and feedback in the Coupled Model Intercomparison Project phase 5 abrupt4xCO2 and Historical experiments are diagnosed, with a focus on their effects on the zonal mean structure of the top-of-the-atmosphere radiation anomalies and implications for the meridional energy transport. It is found that because the greenhouse gas longwave forcing peaks in the low latitudes, it reinforces the equator-to-pole net radiation gradient and accounts for the increase in the poleward energy transport in both hemispheres under global warming. The shortwave forcing by aerosol, ozone, etc. peaks in the Northern Hemisphere and instead implies an interhemispheric energy transport. Although the water vapor feedback also reinforces the equator-to-pole gradient of the net radiation, the temperature and albedo feedback act against it. The feedback tend to offset the zonal mean radiation anomaly caused by the forcing, although the overall feedback effect on the energy transport is rather uncertain, mainly due to the uncertainty in the cloud feedback.", - "Key Points", - " CO2 forcing increases meridional gradient in net radiation Forcing, rather than feedback, accounts for enhanced poleward energy transport Aerosol forcing accounts for an inter-hemispheric transport anomaly" - ], + "abstract": "The distributions of radiative forcing and feedback in the Coupled Model Intercomparison Project phase 5 abrupt4xCO2 and Historical experiments are diagnosed, with a focus on their effects on the zonal mean structure of the top-of-the-atmosphere radiation anomalies and implications for the meridional energy transport. It is found that because the greenhouse gas longwave forcing peaks in the low latitudes, it reinforces the equator-to-pole net radiation gradient and accounts for the increase in the poleward energy transport in both hemispheres under global warming. The shortwave forcing by aerosol, ozone, etc. peaks in the Northern Hemisphere and instead implies an interhemispheric energy transport. Although the water vapor feedback also reinforces the equator-to-pole gradient of the net radiation, the temperature and albedo feedback act against it. The feedback tend to offset the zonal mean radiation anomaly caused by the forcing, although the overall feedback effect on the energy transport is rather uncertain, mainly due to the uncertainty in the cloud feedback. ; ; CO2 forcing increases meridional gradient in net radiation Forcing, rather than feedback, accounts for enhanced poleward energy transport Aerosol forcing accounts for an inter-hemispheric transport anomaly", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -1790,6 +1759,8 @@ "rnsr_id": [], "instituts": [], "teeft": [ + "net radiation", + "feedback", "model intercomparison project phase", "historical experiments", "top-of-the-atmosphere radiation anomalies", @@ -1797,20 +1768,14 @@ "greenhouse gas longwave", "low latitudes", "equator-to-pole net radiation gradient", - "poleward energy transport", - "both hemispheres", - "aerosol ozone" + "poleward energy transport" ] } }, { "uri": "WOS:000332995300011", "title": "Evaluation of interpolation techniques for the creation of gridded daily precipitation ( 1 x 1 km2); Cyprus, 1980-2010", - "abstract": [ - "High-resolution gridded daily data sets are essential for natural resource management and the analyses of climate changes and their effects. This study aims to evaluate the performance of 15 simple or complex interpolation techniques in reproducing daily precipitation at a resolution of 1km(2) over topographically complex areas. Methods are tested considering two different sets of observation densities and different rainfall amounts. We used rainfall data that were recorded at 74 and 145 observational stations, respectively, spread over the 5760km(2) of the Republic of Cyprus, in the Eastern Mediterranean. Regression analyses utilizing geographical copredictors and neighboring interpolation techniques were evaluated both in isolation and combined. Linear multiple regression (LMR) and geographically weighted regression methods (GWR) were tested. These included a step-wise selection of covariables, as well as inverse distance weighting (IDW), kriging, and 3D-thin plate splines (TPS). The relative rank of the different techniques changes with different station density and rainfall amounts. Our results indicate that TPS performs well for low station density and large-scale events and also when coupled with regression models. It performs poorly for high station density. The opposite is observed when using IDW. Simple IDW performs best for local events, while a combination of step-wise GWR and IDW proves to be the best method for large-scale events and high station density. This study indicates that the use of step-wise regression with a variable set of geographic parameters can improve the interpolation of large-scale events because it facilitates the representation of local climate dynamics.", - "Key Points", - " Interpolation of daily rainfall data using 15 spatial interpolation methods Relative skill of interpolation techniques depends on observation density High and low rainfall events should be treated with different techniques" - ], + "abstract": "High-resolution gridded daily data sets are essential for natural resource management and the analyses of climate changes and their effects. This study aims to evaluate the performance of 15 simple or complex interpolation techniques in reproducing daily precipitation at a resolution of 1km(2) over topographically complex areas. Methods are tested considering two different sets of observation densities and different rainfall amounts. We used rainfall data that were recorded at 74 and 145 observational stations, respectively, spread over the 5760km(2) of the Republic of Cyprus, in the Eastern Mediterranean. Regression analyses utilizing geographical copredictors and neighboring interpolation techniques were evaluated both in isolation and combined. Linear multiple regression (LMR) and geographically weighted regression methods (GWR) were tested. These included a step-wise selection of covariables, as well as inverse distance weighting (IDW), kriging, and 3D-thin plate splines (TPS). The relative rank of the different techniques changes with different station density and rainfall amounts. Our results indicate that TPS performs well for low station density and large-scale events and also when coupled with regression models. It performs poorly for high station density. The opposite is observed when using IDW. Simple IDW performs best for local events, while a combination of step-wise GWR and IDW proves to be the best method for large-scale events and high station density. This study indicates that the use of step-wise regression with a variable set of geographic parameters can improve the interpolation of large-scale events because it facilitates the representation of local climate dynamics. ; ; Interpolation of daily rainfall data using 15 spatial interpolation methods Relative skill of interpolation techniques depends on observation density High and low rainfall events should be treated with different techniques", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -1852,14 +1817,14 @@ "teeft": [ "idw", "large-scale events", + "interpolation", + "rainfall data", + "interpolation techniques", "high station density", "high-resolution gridded", "data sets", "natural resource management", - "climate changes", - "complex interpolation techniques", - "complex areas", - "two different sets" + "climate changes" ] } }, @@ -1936,10 +1901,7 @@ { "uri": "WOS:000333885700023", "title": "Cirrus cloud susceptibility to the injection of ice nuclei in the upper troposphere", - "abstract": [ - "Due to their net warming effect, cirrus clouds play a crucial role in the climate system. A recently proposed climate engineering mechanism (CEM) intends to reduce high cloud cover by seeding cirrus clouds with efficient ice nuclei (IN) and therefore cool climate. Here, the susceptibility of cirrus clouds to the injection of ice nuclei in the upper troposphere is investigated in the extended Community Atmospheric Model version 5 (CAM5). Due to large uncertainties associated with the dominant ice nucleation mechanism in cirrus clouds, different control cases were simulated. In addition to pure homogeneous and heterogeneous nucleation, cases with competition between homogeneous and heterogeneous nucleation and different fractions of mineral dust active as IN were considered. Whereas seeding in the pure heterogeneous case leads to a strong warming due to overseeding, an optimal seeding IN concentration of approximately 18 l(-1) was found for the other cases. For the optimal seeding concentration, a reduction in the net cloud forcing (NCF) of up to 2 W m(-2) was simulated, corresponding to a strong cooling effect. To optimize the cooling and minimize the amount of seeding material, globally nonuniform seeding strategies were tested, with minimal seeding in the summer hemisphere and in the tropics. With seeding applied to less than half the globe, an even stronger reduction in the NCF was achieved. This suggests that the CEM could work for an atmosphere even with considerable heterogeneous ice nucleation and that the desired cooling could be obtained without seeding the entire globe.", - "Key Points Cirrus cloud seeding in the upper troposphere was simulated in CAM5 Both cirrus cloud susceptibility and short-term climate response were analyzed Even globally non-uniform injection of IN leads to the desired cooling" - ], + "abstract": "Due to their net warming effect, cirrus clouds play a crucial role in the climate system. A recently proposed climate engineering mechanism (CEM) intends to reduce high cloud cover by seeding cirrus clouds with efficient ice nuclei (IN) and therefore cool climate. Here, the susceptibility of cirrus clouds to the injection of ice nuclei in the upper troposphere is investigated in the extended Community Atmospheric Model version 5 (CAM5). Due to large uncertainties associated with the dominant ice nucleation mechanism in cirrus clouds, different control cases were simulated. In addition to pure homogeneous and heterogeneous nucleation, cases with competition between homogeneous and heterogeneous nucleation and different fractions of mineral dust active as IN were considered. Whereas seeding in the pure heterogeneous case leads to a strong warming due to overseeding, an optimal seeding IN concentration of approximately 18 l(-1) was found for the other cases. For the optimal seeding concentration, a reduction in the net cloud forcing (NCF) of up to 2 W m(-2) was simulated, corresponding to a strong cooling effect. To optimize the cooling and minimize the amount of seeding material, globally nonuniform seeding strategies were tested, with minimal seeding in the summer hemisphere and in the tropics. With seeding applied to less than half the globe, an even stronger reduction in the NCF was achieved. This suggests that the CEM could work for an atmosphere even with considerable heterogeneous ice nucleation and that the desired cooling could be obtained without seeding the entire globe. ; Cirrus cloud seeding in the upper troposphere was simulated in CAM5 Both cirrus cloud susceptibility and short-term climate response were analyzed Even globally non-uniform injection of IN leads to the desired cooling", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -1982,24 +1944,20 @@ "cirrus", "nucleation", "cirrus clouds", + "upper troposphere", "effect cirrus clouds", "crucial role", "climate system", "mechanism cem", "high cloud", - "efficient ice nuclei", - "cool climate" + "efficient ice nuclei" ] } }, { "uri": "WOS:000333885700020", "title": "What controls the interannual variation of the wet season onsets over the Amazon?", - "abstract": [ - "Previous studies have established that sea surface temperature anomalies (SSTAs) in the tropical Pacific and Atlantic are the main forcing of the interannual variation of the wet season onsets in the Amazon. However, this variation appears to be complex and not uniquely determined by SSTAs. What causes such a complexity and to what extent the interannual variation of the wet season onsets is predictable remain unclear. This study suggests that such a complex relationship is the result of several competing processes, which are nonlinearly related to the SSTAs. In particular, three dry season conditions are crucial for determining interannual variation of the wet season onset. (i) A poleward shift of the Southern Hemisphere subtropical jet (SHSJ) over the South American sector, initiated from a wave train-like structure possibly forced by south central Pacific SST patterns, can prevent cold frontal systems from moving northward into the Amazon. This delays cold air incursion and results in late wet season onset over the southern Amazon. (ii) An anomalous anticyclonic center, which enhances westerly wind at 850hPa over the southern Amazon and also the South American low-level jets, leads to moisture export from the southern Amazon to La Plata basin and reduces convective systems that provide elevated diabatic heating. (iii) Smaller convective available potential energy (CAPE) limits local thermodynamically driven convection. Based on the stepwise and partial least squares regressions, these three selected preseasonal conditions (Nino 4, SHSJ, and CAPE) can explain 57% of the total variance of the wet season onset.", - "Key Points", - " The wet season onset over the Amazon is not uniquely deterimined by SSTAs A poleward SHSJ, enhanced U850, and lower CAPE are crucial for delayed onset Selected conditions can explain 57% of the total variance" - ], + "abstract": "Previous studies have established that sea surface temperature anomalies (SSTAs) in the tropical Pacific and Atlantic are the main forcing of the interannual variation of the wet season onsets in the Amazon. However, this variation appears to be complex and not uniquely determined by SSTAs. What causes such a complexity and to what extent the interannual variation of the wet season onsets is predictable remain unclear. This study suggests that such a complex relationship is the result of several competing processes, which are nonlinearly related to the SSTAs. In particular, three dry season conditions are crucial for determining interannual variation of the wet season onset. (i) A poleward shift of the Southern Hemisphere subtropical jet (SHSJ) over the South American sector, initiated from a wave train-like structure possibly forced by south central Pacific SST patterns, can prevent cold frontal systems from moving northward into the Amazon. This delays cold air incursion and results in late wet season onset over the southern Amazon. (ii) An anomalous anticyclonic center, which enhances westerly wind at 850hPa over the southern Amazon and also the South American low-level jets, leads to moisture export from the southern Amazon to La Plata basin and reduces convective systems that provide elevated diabatic heating. (iii) Smaller convective available potential energy (CAPE) limits local thermodynamically driven convection. Based on the stepwise and partial least squares regressions, these three selected preseasonal conditions (Nino 4, SHSJ, and CAPE) can explain 57% of the total variance of the wet season onset. ; ; The wet season onset over the Amazon is not uniquely deterimined by SSTAs A poleward SHSJ, enhanced U850, and lower CAPE are crucial for delayed onset Selected conditions can explain 57% of the total variance", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -2050,16 +2008,16 @@ "rnsr_id": [], "instituts": [], "teeft": [ + "sstas", "interannual variation", + "wet season onset", "southern amazon", "wet season onsets", - "wet season onset", "amazon", "previous studies", "sea surface temperature anomalies sstas", "tropical pacific", - "causes such", - "complex relationship" + "causes such" ] } }, @@ -2247,11 +2205,7 @@ { "uri": "WOS:000332991000059", "title": "Surface warming patterns drive tropical rainfall pattern responses to CO2 forcing on all timescales", - "abstract": [ - "Mechanisms behind regional tropical rainfall responses to CO2 forcing are examined in idealized climate model experiments, traceable to transient forcing scenarios. As previously shown, the pattern of the first-year response of dynamical precipitation change to an abrupt CO2 increase is similar to the century-scale response. It is demonstrated here that this similarity is driven by surface temperature pattern change, not a direct atmospheric circulation response to CO2. This confirms the Warmer get Wetter hypothesis, which emphasizes the role of sea surface temperature pattern change in driving regional tropical precipitation change. Future regional rainfall changes should thus be studied primarily in coupled ocean-atmosphere models.", - "Key Points", - " Regional tropical rainfall change is driven by surface warming patterns Land-sea warming contrasts can drive tropics-wide circulation change The direct CO2 effect is important for mean rainfall change, but not patterns" - ], + "abstract": "Mechanisms behind regional tropical rainfall responses to CO2 forcing are examined in idealized climate model experiments, traceable to transient forcing scenarios. As previously shown, the pattern of the first-year response of dynamical precipitation change to an abrupt CO2 increase is similar to the century-scale response. It is demonstrated here that this similarity is driven by surface temperature pattern change, not a direct atmospheric circulation response to CO2. This confirms the Warmer get Wetter hypothesis, which emphasizes the role of sea surface temperature pattern change in driving regional tropical precipitation change. Future regional rainfall changes should thus be studied primarily in coupled ocean-atmosphere models. ; ; Regional tropical rainfall change is driven by surface warming patterns Land-sea warming contrasts can drive tropics-wide circulation change The direct CO2 effect is important for mean rainfall change, but not patterns", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -2349,11 +2303,7 @@ { "uri": "WOS:000332990500046", "title": "The dependence of transient climate sensitivity and radiative feedbacks on the spatial pattern of ocean heat uptake", - "abstract": [ - "The effect of ocean heat uptake (OHU) on transient global warming is studied in a multimodel framework. Simple heat sinks are prescribed in shallow aquaplanet ocean mixed layers underlying atmospheric general circulation models independently and combined with CO2 forcing. Sinks are localized to either tropical or high latitudes, representing distinct modes of OHU found in coupled simulations. Tropical OHU produces modest cooling at all latitudes, offsetting only a fraction of CO2 warming. High-latitude OHU produces three times more global mean cooling in a strongly polar-amplified pattern. Global sensitivities in each scenario are set primarily by large differences in local shortwave cloud feedbacks, robust across models. Differences in atmospheric energy transport set the pattern of temperature change. Results imply that global and regional warming rates depend sensitively on regional ocean processes setting the OHU pattern, and that equilibrium climate sensitivity cannot be reliably estimated from transient observations.", - "Key Points", - "Climate response depends strongly on spatial pattern of ocean heat uptake Different radiative feedbacks govern transient and equilibrium CO2 warming Results are robust across an ensemble of aquaplanet climate models" - ], + "abstract": "The effect of ocean heat uptake (OHU) on transient global warming is studied in a multimodel framework. Simple heat sinks are prescribed in shallow aquaplanet ocean mixed layers underlying atmospheric general circulation models independently and combined with CO2 forcing. Sinks are localized to either tropical or high latitudes, representing distinct modes of OHU found in coupled simulations. Tropical OHU produces modest cooling at all latitudes, offsetting only a fraction of CO2 warming. High-latitude OHU produces three times more global mean cooling in a strongly polar-amplified pattern. Global sensitivities in each scenario are set primarily by large differences in local shortwave cloud feedbacks, robust across models. Differences in atmospheric energy transport set the pattern of temperature change. Results imply that global and regional warming rates depend sensitively on regional ocean processes setting the OHU pattern, and that equilibrium climate sensitivity cannot be reliably estimated from transient observations. ; ; Climate response depends strongly on spatial pattern of ocean heat uptake Different radiative feedbacks govern transient and equilibrium CO2 warming Results are robust across an ensemble of aquaplanet climate models", "publication_year": 2014, "source": "GEOPHYSICAL RESEARCH LETTERS", "affiliations": [ @@ -2717,6 +2667,7 @@ { "uri": "WOS:000334908300017", "title": "A multimodel examination of climate extremes in an idealized geoengineering experiment", + "abstract": "", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [ @@ -2782,6 +2733,7 @@ { "uri": "WOS:000334908300040", "title": "Ammonia emissions in the United States, European Union, and China derived by high-resolution inversion of ammonium wet deposition data: Interpretation with a new agricultural emissions inventory (MASAGE_NH3)", + "abstract": "", "publication_year": 2014, "source": "JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES", "affiliations": [