The diurnal surface temperature range （DTR） has become significantly smaller over the Tibetan Plateau （TP） but larger in southeastern China, despite the daily mean surface temperature having increased steadily in ...The diurnal surface temperature range （DTR） has become significantly smaller over the Tibetan Plateau （TP） but larger in southeastern China, despite the daily mean surface temperature having increased steadily in both areas during recent decades. Based on ERA-Interim reanalysis data covering 1979-2012, this study shows that the weakened DTR over TP is caused by stronger warming of daily minimum surface temperature （Tmin） and a weak cooling of the daily maximum surface temper- ature （Tmax）; meanwhile, the enhanced DTR over southeastern China is mainly associated with a relatively stronger/weaker warming of Tmax/Tmin. A further quantitative analysis of DTR changes through a process-based decomposition method-- the Coupled Surface-Atmosphere Climate Feedback Response Analysis Method （CFRAM）--indicates that changes in radia- tive processes are mainly responsible for the decreased DTR over the TR In particular, the increased low-level cloud cover tends to induce the radiative cooling/warming during daytime/nighttime, and the increased water vapor helps to decrease the DTR through the stronger radiative wanning during nighttime than daytime. Contributions from the changes in all radiative processes （over -2℃） are compensated for by those from the stronger decreased surface sensible heat flux during daytime than during nighttime （approximately 2.5℃）, but are co-contributed by the changes in atmospheric dynamics （approximately -0.4℃） and the stronger increased latent heat flux during daytime （approximately -0.8℃）. In contrast, the increased DTR over southeastern China is mainly contributed by the changes in cloud, water vapor and atmospheric dynamics. The changes in surface heat fluxes have resulted in a decrease in DTR over southeastern China.展开更多
This study uses the coupled atmosphere–surface climate feedback–response analysis method（CFRAM） to analyze the surface temperature biases in the Flexible Global Ocean–Atmosphere–Land System model, spectral versi...This study uses the coupled atmosphere–surface climate feedback–response analysis method（CFRAM） to analyze the surface temperature biases in the Flexible Global Ocean–Atmosphere–Land System model, spectral version 2（FGOALS-s2）in January and July. The process-based decomposition of the surface temperature biases, defined as the difference between the model and ERA-Interim during 1979–2005, enables us to attribute the model surface temperature biases to individual radiative processes including ozone, water vapor, cloud, and surface albedo; and non-radiative processes including surface sensible and latent heat fluxes, and dynamic processes at the surface and in the atmosphere. The results show that significant model surface temperature biases are almost globally present, are generally larger over land than over oceans, and are relatively larger in summer than in winter. Relative to the model biases in non-radiative processes, which tend to dominate the surface temperature biases in most parts of the world, biases in radiative processes are much smaller, except in the sub-polar Antarctic region where the cold biases from the much overestimated surface albedo are compensated for by the warm biases from nonradiative processes. The larger biases in non-radiative processes mainly lie in surface heat fluxes and in surface dynamics,which are twice as large in the Southern Hemisphere as in the Northern Hemisphere and always tend to compensate for each other. In particular, the upward/downward heat fluxes are systematically underestimated/overestimated in most parts of the world, and are mainly compensated for by surface dynamic processes including the increased heat storage in deep oceans across the globe.展开更多
The Ross-Amundsen sector is experiencing an accelerating warming trend and a more intensive advective influx of marine air streams.As a result,massive surface melting events of the ice shelf are occurring more frequen...The Ross-Amundsen sector is experiencing an accelerating warming trend and a more intensive advective influx of marine air streams.As a result,massive surface melting events of the ice shelf are occurring more frequently,which puts the West Antarctica Ice Sheet at greater risk of degradation.This study shows the connection between surface melting and the prominent intrusion of warm and humid air flows from lower latitudes.By applying the Climate Feedback-Response Analysis Method(CFRAM),the temporal surge of the downward longwave(LW)fluxes over the surface of the Ross Ice Shelf(RIS)and adjacent regions are identified for four historically massive RIS surface melting events.The melting events are decomposed to identify which physical mechanisms are the main contributors.We found that intrusions of warm and humid airflow from lower latitudes are conducive to warm air temperature and water vapor anomalies,as well as cloud development.These changes exert a combined impact on the abnormal enhancement of the downward LW surface radiative fluxes,significantly contributing to surface warming and the resultant massive melting of ice.展开更多
Previous studies have found amplified warming over Europe-West Asia and Northeast Asia in summer since the mid- 1990s relative to elsewhere on the Eurasian continent, but the cause of the amplification in these two re...Previous studies have found amplified warming over Europe-West Asia and Northeast Asia in summer since the mid- 1990s relative to elsewhere on the Eurasian continent, but the cause of the amplification in these two regions remains unclear. In this study, we compared the individual contributions of influential factors for amplified warming over these two regions through a quantitative diagnostic analysis based on CFRAM (climate feedback-response analysis method). The changes in surface air temperature are decomposed into the partial changes due to radiative processes (including CO2 concentration, incident solar radiation at the top of the atmosphere, surface albedo, water vapor content, ozone concentration, and clouds) and non-radiative processes (including surface sensible heat flux, surface latent heat flux, and dynamical processes). Our results suggest that the enhanced warming over these two regions is primarily attributable to changes in the radiative processes, which contributed 0.62 and 0.98 K to the region-averaged warming over Europe-West Asia (1.00 K) and Northeast Asia (1.02 K), respectively. Among the radiative processes, the main drivers were clouds, CO2 concentration, and water vapor content. The cloud term alone contributed to the mean amplitude of warming by 0.40 and 0.85 K in Europe-West Asia and Northeast Asia, respectively. In comparison, the non-radiative processes made a much weaker contribution due to the combined impact of surface sensible heat flux, surface latent heat flux, and dynamical processes, accounting for only 0.38 K for the warming in Europe-West Asia and 0.05 K for the warming in Northeast Asia. The resemblance between the influential factors for the amplified warming in these two separate regions implies a common dynamical origin. Thus, this validates the possibility that they originate from the Silk Road pattern.展开更多
Based on an attribution analysis of the global mean temperature biases in the Flexible Global Ocean- AtmOsphere-Land System model, spectral version 2 （FGOALS-s2） through a coupled atmosphere-surface ch- mate feedb...Based on an attribution analysis of the global mean temperature biases in the Flexible Global Ocean- AtmOsphere-Land System model, spectral version 2 （FGOALS-s2） through a coupled atmosphere-surface ch- mate feedback-response analysis method （CFRAM）, the model＇s global surface-atmosphere energy balance in boreal winter and summer is examined. Within the en- ergy-balance-based CFRAM system, the model temperature biases are attributed to energy perturbations resulting from model biases in individual radiative and non-radia- tive processes in the atmosphere and at the surface. The results show that, although the global mean surface tem- perature （Ts） bias is only 0.38 K in January and 1.70 K in July, and the atmospheric temperature （Ta） biases from the troposphere to the stratosphere are only around ＋3 K at most, the temperature biases due to model biases in rep- resenting the individual radiative and non-radiative proc- esses are considerably large （over -4-10 K at most）. Spe- cifically, the global cold radiative Ts bias, mainly due to the overestimated surface albedo, is compensated for by the global warm non-radiative Ts bias that is mainly due to the overestimated downward surface heat fluxes. The model biases in non-radiative processes in the lower tro- posphere （up to 5-15 K） are relatively much larger than in upper levels, which are mainly responsible for the warm Ta biases there. In contrast, the global mean cold ira biases in the mid-to-upper troposphere are mainly dominated by radiative processes. The warm/cold Ta biases in the lower/upper stratosphere are dominated by non-radiative processes, while the warm ira biases in the mid-strato- sphere can be attributed to the radiative ozone feedback process.展开更多
基金jointly supported by the China Meteorological Administration Special Public Welfare Research Fund(Grant No.GYHY201406001)the National Natural Science Foundation of China(Grant Nos.91437105,41575041 and 41430533)Special Foundation for National Commonweal Institutes of China(Grant No.IUMKY201614)
文摘The diurnal surface temperature range （DTR） has become significantly smaller over the Tibetan Plateau （TP） but larger in southeastern China, despite the daily mean surface temperature having increased steadily in both areas during recent decades. Based on ERA-Interim reanalysis data covering 1979-2012, this study shows that the weakened DTR over TP is caused by stronger warming of daily minimum surface temperature （Tmin） and a weak cooling of the daily maximum surface temper- ature （Tmax）; meanwhile, the enhanced DTR over southeastern China is mainly associated with a relatively stronger/weaker warming of Tmax/Tmin. A further quantitative analysis of DTR changes through a process-based decomposition method-- the Coupled Surface-Atmosphere Climate Feedback Response Analysis Method （CFRAM）--indicates that changes in radia- tive processes are mainly responsible for the decreased DTR over the TR In particular, the increased low-level cloud cover tends to induce the radiative cooling/warming during daytime/nighttime, and the increased water vapor helps to decrease the DTR through the stronger radiative wanning during nighttime than daytime. Contributions from the changes in all radiative processes （over -2℃） are compensated for by those from the stronger decreased surface sensible heat flux during daytime than during nighttime （approximately 2.5℃）, but are co-contributed by the changes in atmospheric dynamics （approximately -0.4℃） and the stronger increased latent heat flux during daytime （approximately -0.8℃）. In contrast, the increased DTR over southeastern China is mainly contributed by the changes in cloud, water vapor and atmospheric dynamics. The changes in surface heat fluxes have resulted in a decrease in DTR over southeastern China.
基金jointly supported by projects XDA11010402 GYHY201406001the National Basic Key Project (973) 2010CB428603 and 2010CB950400
文摘This study uses the coupled atmosphere–surface climate feedback–response analysis method（CFRAM） to analyze the surface temperature biases in the Flexible Global Ocean–Atmosphere–Land System model, spectral version 2（FGOALS-s2）in January and July. The process-based decomposition of the surface temperature biases, defined as the difference between the model and ERA-Interim during 1979–2005, enables us to attribute the model surface temperature biases to individual radiative processes including ozone, water vapor, cloud, and surface albedo; and non-radiative processes including surface sensible and latent heat fluxes, and dynamic processes at the surface and in the atmosphere. The results show that significant model surface temperature biases are almost globally present, are generally larger over land than over oceans, and are relatively larger in summer than in winter. Relative to the model biases in non-radiative processes, which tend to dominate the surface temperature biases in most parts of the world, biases in radiative processes are much smaller, except in the sub-polar Antarctic region where the cold biases from the much overestimated surface albedo are compensated for by the warm biases from nonradiative processes. The larger biases in non-radiative processes mainly lie in surface heat fluxes and in surface dynamics,which are twice as large in the Southern Hemisphere as in the Northern Hemisphere and always tend to compensate for each other. In particular, the upward/downward heat fluxes are systematically underestimated/overestimated in most parts of the world, and are mainly compensated for by surface dynamic processes including the increased heat storage in deep oceans across the globe.
基金supported by the National Natural Science Foundation of China (Grant Nos. 42075028 and 42222502)the Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) (Grant SML2021SP302)
文摘The Ross-Amundsen sector is experiencing an accelerating warming trend and a more intensive advective influx of marine air streams.As a result,massive surface melting events of the ice shelf are occurring more frequently,which puts the West Antarctica Ice Sheet at greater risk of degradation.This study shows the connection between surface melting and the prominent intrusion of warm and humid air flows from lower latitudes.By applying the Climate Feedback-Response Analysis Method(CFRAM),the temporal surge of the downward longwave(LW)fluxes over the surface of the Ross Ice Shelf(RIS)and adjacent regions are identified for four historically massive RIS surface melting events.The melting events are decomposed to identify which physical mechanisms are the main contributors.We found that intrusions of warm and humid airflow from lower latitudes are conducive to warm air temperature and water vapor anomalies,as well as cloud development.These changes exert a combined impact on the abnormal enhancement of the downward LW surface radiative fluxes,significantly contributing to surface warming and the resultant massive melting of ice.
基金supported by the National Key Research and Development Program of China(Grant Nos.2018YFA0606403 and 2015CB453202)the National Natural Science Foundation of China(Grant Nos.41790473 and 41421004)
文摘Previous studies have found amplified warming over Europe-West Asia and Northeast Asia in summer since the mid- 1990s relative to elsewhere on the Eurasian continent, but the cause of the amplification in these two regions remains unclear. In this study, we compared the individual contributions of influential factors for amplified warming over these two regions through a quantitative diagnostic analysis based on CFRAM (climate feedback-response analysis method). The changes in surface air temperature are decomposed into the partial changes due to radiative processes (including CO2 concentration, incident solar radiation at the top of the atmosphere, surface albedo, water vapor content, ozone concentration, and clouds) and non-radiative processes (including surface sensible heat flux, surface latent heat flux, and dynamical processes). Our results suggest that the enhanced warming over these two regions is primarily attributable to changes in the radiative processes, which contributed 0.62 and 0.98 K to the region-averaged warming over Europe-West Asia (1.00 K) and Northeast Asia (1.02 K), respectively. Among the radiative processes, the main drivers were clouds, CO2 concentration, and water vapor content. The cloud term alone contributed to the mean amplitude of warming by 0.40 and 0.85 K in Europe-West Asia and Northeast Asia, respectively. In comparison, the non-radiative processes made a much weaker contribution due to the combined impact of surface sensible heat flux, surface latent heat flux, and dynamical processes, accounting for only 0.38 K for the warming in Europe-West Asia and 0.05 K for the warming in Northeast Asia. The resemblance between the influential factors for the amplified warming in these two separate regions implies a common dynamical origin. Thus, this validates the possibility that they originate from the Silk Road pattern.
基金jointly supported by the Special Fund for Public Welfare Industry(Meteorology)(Grant No.GYHY201406001)Science Foundation of the Chinese Academy of Sciences(Grant No.XDA11010402)the National Natural Science Foundation of China(Grant No.91437105)
文摘Based on an attribution analysis of the global mean temperature biases in the Flexible Global Ocean- AtmOsphere-Land System model, spectral version 2 （FGOALS-s2） through a coupled atmosphere-surface ch- mate feedback-response analysis method （CFRAM）, the model＇s global surface-atmosphere energy balance in boreal winter and summer is examined. Within the en- ergy-balance-based CFRAM system, the model temperature biases are attributed to energy perturbations resulting from model biases in individual radiative and non-radia- tive processes in the atmosphere and at the surface. The results show that, although the global mean surface tem- perature （Ts） bias is only 0.38 K in January and 1.70 K in July, and the atmospheric temperature （Ta） biases from the troposphere to the stratosphere are only around ＋3 K at most, the temperature biases due to model biases in rep- resenting the individual radiative and non-radiative proc- esses are considerably large （over -4-10 K at most）. Spe- cifically, the global cold radiative Ts bias, mainly due to the overestimated surface albedo, is compensated for by the global warm non-radiative Ts bias that is mainly due to the overestimated downward surface heat fluxes. The model biases in non-radiative processes in the lower tro- posphere （up to 5-15 K） are relatively much larger than in upper levels, which are mainly responsible for the warm Ta biases there. In contrast, the global mean cold ira biases in the mid-to-upper troposphere are mainly dominated by radiative processes. The warm/cold Ta biases in the lower/upper stratosphere are dominated by non-radiative processes, while the warm ira biases in the mid-strato- sphere can be attributed to the radiative ozone feedback process.
