大气科学2012，Vol.36Issue(3)：443-457,15.DOI:10.3878/j.issn.1006-9895.2011.11101
2009年秋至2010年春我国西南地区严重干旱的成因分析
Analyses of the Causes of Severe Drought Occurring in Southwest China from the Fall of 2009 to the Spring of 2010
摘要
Abstract
A severe drought occurred in Southwest China from the fall of 2009 to the spring of 2010. Either its persistent time and area or decreased amount of rainfall were less observed during the last 50 years. Thus, in this paper, the occurring causes of this drought are analyzed by using the ERA-40 reanalysis data and SST data from the impacts of thermal anomalies in the tropical western Pacific (TWP) and the tropical Indian Ocean (TIO) on the atmospheric circulation over the TWP and South Asia. The results show that during the period from the fall of 2009 to the spring of 2010, both the TWP and the TIO were in a warming state. Under the common thermal effect of both oceans, a strong anticyclonic anomalous circulation appeared in the lower troposphere over the TWP and the South China Sea, which caused not only the strengthening of the southwest flow anomaly, but also the appearance of a low trough anomaly over South China and Central China. In this case, the northwest flow anomaly and descending flow anomaly behind the trough controlled the eastern part of the Tibetan Plateau, and water vapor was difficultly transported from the Bay of Bengal into the Yunnan-Guizhou Plateau (Yun Gui Plateau in short). Thus, less rainfall for a long time was caused in this region. Moreover, the analysis results also show that the circulation anomaly over the mid- and high latitudes had an important impact on the severe drought Since the polar wave guide of quasi-stationary planetary wave propagations over the high latitudes was stronger, but the low-latitude wave guide was weaker from the fall of 2009 to the spring of 2010, which led to convergence and divergence of the wave E-P fluxes for quasi-stationary planetary waves in the upper troposphere and the stratosphere over the region about 60° N and in the middle and upper troposphere over the region about 35°N, respectively. Thus, the zonal mean wind was weakened in the upper troposphere and the stratosphere over the region about 60°N, but it was strengthened in the upper troposphere over the region about 35°N. This caused an obviously negative phase of the AO (Arctic Oscillation) and brought strong winter monsoon and eastward tracks of cold waves into East Asia, which led to a weakening of cold air arriving in Southwest China. Thereby, the persistent severe drought occurred in Southwest China.关键词
干旱/热带西太平洋/东亚冬季风/准定常行星波传播Key words
drought/tropical western Pacific/East Asian winter monsoon/quasi-stationary planetary wave propagation分类
天文与地球科学引用本文复制引用
黄荣辉,刘永,王林,王磊..2009年秋至2010年春我国西南地区严重干旱的成因分析[J].大气科学,2012,36(3):443-457,15.基金项目
国家公益性行业(气象)科研专项GYHY201006021,国家重点基础研究发展计划项目2010CB950403、2009CB421405 （气象）
