Interdecadal change of summer precipitation over Eastern China around the late-1990s and associated circulation anomalies,internal dynamical causes  

作　　者：HUANG RongHui LIU Yong FENG Tao 

机构地区：[1]State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics,Chinese Academy of Sciences [2]Center for Monsoon System Research, Institute of Atmospheric Physics, Chinese Academy of Sciences

出　　处：《Chinese Science Bulletin》2013年第12期1339-1349,共11页

基　　金：supported by National Key Basic Research Program of China (2009CB421405, 2010CB950403);the Special Scientific Research Fund for Meteorological Public Welfare Profession of China (GYHY201006021);the National Natural Science Foundation of China (41175055 and 40905027)

摘　　要：Observational study indicated that the summer precipitation over Eastern China experienced a notable interdecadal change around the late-1990s. Accompanying this interdecadal change, the dominant mode of anomalous precipitation switched from a meridional triple pattern to a dipole pattern, showing a "south-flood-north-drought" structure (with the exception of the Yangtze River Valley). This interdecadal change of summer precipitation over Eastern China was associated with circulation anomalies in the middle/upper troposphere over East Asia, such as changes in winds and corresponding divergence, vertical motion and moisture transportation (divergence), which all exhibit remarkable meridional dipole structures. Furthermore, on the internal dynamic and thermodynamic aspects, the present study investigated the influence of the midtroposphere zonal and meridional flow changes over East Asia on the interdecadal change around the late-1990s. Results suggested that, during 1999-2010, the East Asia subtropical westerly jet weakened and shifted poleward, forming a meridional dipole feature in anomalous zonal flow. This anomalous zonal flow, on one hand, induced changes in three teleconnection patterns over the Eurasian continent, namely the "Silk Road" pattern along the subtropical upper troposphere westerly jet, the East Asia/Pacific (EAP) pattern along the East Asian coast, and the Eurasia (EU) pattern along the polar jet; on the other hand, it brought about cold advection over Northern China, and warm advection over Southern China in the mid-troposphere. Through these two ways, the changes in the zonal flow induced descent over Northern China and ascent over Southern China, which resulted in the anomalous "south-flood-north-drought" feature of the summer precipitation over Eastern China during 1999-2010.Observational study indicated that the summer precipitation over Eastern China experienced a notable interdecadal change around the late-1990s. Accompanying this interdecadal change, the dominant mode of anomalous precipitation switched from a meridional triple pattern to a dipole pattern, showing a ＂south-flood-north-drought＂ structure （wiih the exception of the Yangtze River Valley）. This interdecadal change of summer precipitation over Eastern China was associated with circulation anomalies in the middle/upper troposphere over East Asia, such as changes in winds and corresponding divergence, vertical motion and moisture transportation （divergence）, which all exhibit remarkable meridional dipole structures. Furthermore, on the internal dynamic and thermodynamic aspects, the present study investigated the influence of the midtroposphere zonal and meridional flow changes over East Asia on the interdecadal change around the late-1990s. Results suggested that, during 1999-2010, the East Asia subtropical westerly jet weakened and shifted poleward, forming a meridional dipole feature in anomalous zonal flow. This anomalous zonal flow, on one hand, induced changes in three teleconnection patterns over the Eurasian continent, namely the ＂Silk Road＂ pattern along the subtropical upper troposphere westerly jet, the East Asia/Pacific （EAP） pattern along the East Asian coast, and the Eurasia （EU） pattern along the polar jet; on the other hand, it brought about cold advection over Northern China, and warm advection over Southern China in the mid-troposphere. Through these two ways, the changes in the zonal flow induced descent over Northern China and ascent over Southem China, which resulted in the anomalous ＂south-flood-north-drought＂ feature of the summer precipilation over Eastern China during 1999-2010.

关 键 词：大气环流异常 中国东部地区 年代际变化 内部动力学 夏季降水 后期 副热带西风急流 原因 

分 类 号：P434[天文地球—大气科学及气象学] P467