为了探究温室气体(greenhouse gas,GHG)和土地利用/覆盖变化(land use and land cover change,LULCC)对于地面气温日较差(diurnal temperature range,DTR)的影响及相对贡献作用,本文采用耦合地球系统模式(Community Earth System Model...为了探究温室气体(greenhouse gas,GHG)和土地利用/覆盖变化(land use and land cover change,LULCC)对于地面气温日较差(diurnal temperature range,DTR)的影响及相对贡献作用,本文采用耦合地球系统模式(Community Earth System Model)进行了模拟研究。模拟结果表明:GHG浓度的增加导致北半球中高纬度地区年平均DTR显著降低,但GHG引起DTR变化存在显著的季节差异,在暖季和冷季,北美地区和西伯利亚地区呈现出相反的变化特征,GHG增加对于中高纬度地区年平均DTR的降低作用主要是由冷季贡献的。LULCC通过影响叶面积指数和地面反照率显著降低东亚、南亚、欧洲和北美东部地区的DTR。通过创建一种新的分析方式,本文研究了GHG和LULCC对DTR的相对贡献作用,在北半球高纬度地区,GHG在DTR的变化中扮演着主导作用,但在中纬度地区和南亚地区,无论是DTR变化数值的正负符号还是大小,LULCC都起着显著的影响作用。展开更多
Western China experienced an extreme hot summer in 2015,breaking a number of temperature records.The summer mean surface air temperature(SAT)anomaly was twice the interannual variability.The hottest daytime temperatur...Western China experienced an extreme hot summer in 2015,breaking a number of temperature records.The summer mean surface air temperature(SAT)anomaly was twice the interannual variability.The hottest daytime temperature(TXx)and warmest night-time temperature(TNx)were the highest in China since 1964.This extreme hot summer occurred in the context of steadily increasing temperatures in recent decades.We carried out a set of experiments to evaluate the extent to which the changes in sea surface temperature(SST)/sea ice extent(SIE)and anthropogenic forcing drove the severity of the extreme summer of 2015 in western China.Our results indicate that about 65%–72% of the observed changes in the seasonal mean SAT and the daily maximumand daily minimum(Tmin)temperatures over western China resulted from changes in boundary forcings,including the SST/SIE and anthropogenic forcing.For the relative role of individual forcing,the direct impact of changes in anthropogenic forcing explain about 42% of the SAT warming and 60%(40%)of the increase in TNxand Tmin(TXxand Tmax)in the model response.The changes in SST/SIE contributed to the remaining surface warming and the increase in hot extremes,which are mainly the result of changes in the SST over the Pacific Ocean,where a super El Ni?o event occurred.Our study indicates a prominent role for the direct impact of anthropogenic forcing in the severity of the extreme hot summer in western China in 2015,although the changes in SST/SIE,as well as the internal variability of the atmosphere,also made a contribution.展开更多
基金supported by the National Natural Science Foundation of China[grant number 42088101] and the National Natural Science Foundation of China[grant number 42005020].
文摘为了探究温室气体(greenhouse gas,GHG)和土地利用/覆盖变化(land use and land cover change,LULCC)对于地面气温日较差(diurnal temperature range,DTR)的影响及相对贡献作用,本文采用耦合地球系统模式(Community Earth System Model)进行了模拟研究。模拟结果表明:GHG浓度的增加导致北半球中高纬度地区年平均DTR显著降低,但GHG引起DTR变化存在显著的季节差异,在暖季和冷季,北美地区和西伯利亚地区呈现出相反的变化特征,GHG增加对于中高纬度地区年平均DTR的降低作用主要是由冷季贡献的。LULCC通过影响叶面积指数和地面反照率显著降低东亚、南亚、欧洲和北美东部地区的DTR。通过创建一种新的分析方式,本文研究了GHG和LULCC对DTR的相对贡献作用,在北半球高纬度地区,GHG在DTR的变化中扮演着主导作用,但在中纬度地区和南亚地区,无论是DTR变化数值的正负符号还是大小,LULCC都起着显著的影响作用。
基金Supported by the National Natural Science Foundation of China(416750788,U1502233,and 41320104007)Youth Innovation Promotion Association of Chinese Academy of Sciences(2018102)Natural Environment Research Council via National Centre for Atmospheric Science of UK
文摘Western China experienced an extreme hot summer in 2015,breaking a number of temperature records.The summer mean surface air temperature(SAT)anomaly was twice the interannual variability.The hottest daytime temperature(TXx)and warmest night-time temperature(TNx)were the highest in China since 1964.This extreme hot summer occurred in the context of steadily increasing temperatures in recent decades.We carried out a set of experiments to evaluate the extent to which the changes in sea surface temperature(SST)/sea ice extent(SIE)and anthropogenic forcing drove the severity of the extreme summer of 2015 in western China.Our results indicate that about 65%–72% of the observed changes in the seasonal mean SAT and the daily maximumand daily minimum(Tmin)temperatures over western China resulted from changes in boundary forcings,including the SST/SIE and anthropogenic forcing.For the relative role of individual forcing,the direct impact of changes in anthropogenic forcing explain about 42% of the SAT warming and 60%(40%)of the increase in TNxand Tmin(TXxand Tmax)in the model response.The changes in SST/SIE contributed to the remaining surface warming and the increase in hot extremes,which are mainly the result of changes in the SST over the Pacific Ocean,where a super El Ni?o event occurred.Our study indicates a prominent role for the direct impact of anthropogenic forcing in the severity of the extreme hot summer in western China in 2015,although the changes in SST/SIE,as well as the internal variability of the atmosphere,also made a contribution.
