基于1958~2002年欧洲中期数值预报中心(ECMWF)提供的ERA-40再分析资料和美国气象环境预报中心/美国国家大气研究中心提供的NCEP/NCAR再分析资料研究了夏季南亚高压的东西偏向与亚洲季风区对流层顶附近水汽输送之间的关系。结果表明:(1)...基于1958~2002年欧洲中期数值预报中心(ECMWF)提供的ERA-40再分析资料和美国气象环境预报中心/美国国家大气研究中心提供的NCEP/NCAR再分析资料研究了夏季南亚高压的东西偏向与亚洲季风区对流层顶附近水汽输送之间的关系。结果表明:(1)南亚高压的东西偏向对上对流层200 h Pa水汽高值中心的位置影响较小,主要影响其强度,对100 h Pa水汽高值中心的位置和强度有着较强的影响,而对平流层下部70 h Pa的水汽分布几乎没有影响。(2)南亚高压偏东年,高原上空和高原南部的垂直上升运动较强,在西风急流的共同作用下可将低层丰富的水汽向上输送,使200 h Pa和100 h Pa的水汽高值中心位于高原上空,而100 h Pa南亚高压范围内偏北风和偏东风增强,在水平输送的作用下使高值中心周围水汽的分布形态与高压中心的分布形态一致。(3)南亚高压偏西年,沿着高原西部的地形抬升作用比高原上空的对流上升运动更强,西风急流北移,对流层顶附近在60°E^80°E范围内形成气旋式环流,因此水汽高值中心向西偏移到伊朗高原。(4)南亚高压范围内200 h Pa的温度异常分布与水汽的异常分布一致,暖中心有利于高水汽的生成。而100 h Pa的温度异常分布与水汽异常分布相反,暖中心对应异常偏低的水汽,说明南亚高压范围内下平流层的水汽分布受环流场和温度场共同作用的影响。该研究对理解南亚高压东西偏向机制及提高亚洲气候预测有一定的参考意义。展开更多
Drought events have become more frequent and intense over East Asia in recent decades,leading to huge socioeconomic impacts.Although the droughts have been studied extensively by cases or for individual regions,their ...Drought events have become more frequent and intense over East Asia in recent decades,leading to huge socioeconomic impacts.Although the droughts have been studied extensively by cases or for individual regions,their leading variability and associated causes remain unclear.Based on the Standardized Precipitation Evapotranspiration Index(SPEI)and ERA5 reanalysis product from 1979 to 2020,this study evealuates the severity of spring droughts in East Asia and investigates their variations and associated drivers.The results indicate that North China and Mongolia have experienced remarkable trends toward dryness during spring in recent decades,while southwestern China has witnessed an opposite trend toward wetness.The first Empirical Orthogonal Function mode of SPEI variability reveals a similar seesawing pattern,with more severe dryness in northwestern China,Mongolia,North China,South Korea,and Japan but increased wetness in Southwestern China and southeast Asia.Further investigation reveals that the anomalously dry(wet)surface in North(Southwestern)China is significantly associated with anomalously high(low)temperature,less(more)precipitation,and reduced(increased)soil moisture during the previous winter and early spring,regulated by an anomalous anticyclone(cyclone)and thus reduced(increased)water vapor convergence.The spring dry-wet pattern in East Asia is also linked to cold sea surface temperature anomalies in the central-eastern Pacific.The findings of this study have important implications for improving the prediction of spring drought events in East Asia.展开更多
文摘基于1958~2002年欧洲中期数值预报中心(ECMWF)提供的ERA-40再分析资料和美国气象环境预报中心/美国国家大气研究中心提供的NCEP/NCAR再分析资料研究了夏季南亚高压的东西偏向与亚洲季风区对流层顶附近水汽输送之间的关系。结果表明:(1)南亚高压的东西偏向对上对流层200 h Pa水汽高值中心的位置影响较小,主要影响其强度,对100 h Pa水汽高值中心的位置和强度有着较强的影响,而对平流层下部70 h Pa的水汽分布几乎没有影响。(2)南亚高压偏东年,高原上空和高原南部的垂直上升运动较强,在西风急流的共同作用下可将低层丰富的水汽向上输送,使200 h Pa和100 h Pa的水汽高值中心位于高原上空,而100 h Pa南亚高压范围内偏北风和偏东风增强,在水平输送的作用下使高值中心周围水汽的分布形态与高压中心的分布形态一致。(3)南亚高压偏西年,沿着高原西部的地形抬升作用比高原上空的对流上升运动更强,西风急流北移,对流层顶附近在60°E^80°E范围内形成气旋式环流,因此水汽高值中心向西偏移到伊朗高原。(4)南亚高压范围内200 h Pa的温度异常分布与水汽的异常分布一致,暖中心有利于高水汽的生成。而100 h Pa的温度异常分布与水汽异常分布相反,暖中心对应异常偏低的水汽,说明南亚高压范围内下平流层的水汽分布受环流场和温度场共同作用的影响。该研究对理解南亚高压东西偏向机制及提高亚洲气候预测有一定的参考意义。
基金National Natural Science Foundation of China(42230603,42275020)Guangdong Major Project of Basic and Applied Basic Research(2020B0301030004)+3 种基金Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies(2020B1212060025)Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(311021001)Open Fund of State Key Laboratory of Satellite Ocean Environment Dynamics,Second Institute of Oceanography,MNR(QNHX2310)Future Earth Early-Career Fellowship of the Future Earth Global Secretariat Hub China。
文摘Drought events have become more frequent and intense over East Asia in recent decades,leading to huge socioeconomic impacts.Although the droughts have been studied extensively by cases or for individual regions,their leading variability and associated causes remain unclear.Based on the Standardized Precipitation Evapotranspiration Index(SPEI)and ERA5 reanalysis product from 1979 to 2020,this study evealuates the severity of spring droughts in East Asia and investigates their variations and associated drivers.The results indicate that North China and Mongolia have experienced remarkable trends toward dryness during spring in recent decades,while southwestern China has witnessed an opposite trend toward wetness.The first Empirical Orthogonal Function mode of SPEI variability reveals a similar seesawing pattern,with more severe dryness in northwestern China,Mongolia,North China,South Korea,and Japan but increased wetness in Southwestern China and southeast Asia.Further investigation reveals that the anomalously dry(wet)surface in North(Southwestern)China is significantly associated with anomalously high(low)temperature,less(more)precipitation,and reduced(increased)soil moisture during the previous winter and early spring,regulated by an anomalous anticyclone(cyclone)and thus reduced(increased)water vapor convergence.The spring dry-wet pattern in East Asia is also linked to cold sea surface temperature anomalies in the central-eastern Pacific.The findings of this study have important implications for improving the prediction of spring drought events in East Asia.
