云南夏季降水量在21世纪初的突变减少及原因分析

Abrupt Decrease of Yunnan Summer Rainfall in the Early 21st Century and Its Possible Reasons

利用1960—2013年云南125个台站观测资料和美国环境预报中心/国家大气研究中心再分析资料,以及1960—2013年美国国家海洋和大气管理局(NOAA)提供的逐月平均全球海表温度资料,分析了云南地区降水量变化的特征以及与之相关联的大气环流背景场。分析结果表明:云南降水量在2002年发生了一次显著减少的突变,而这次突变主要是由于夏季降水的明显减少而形成的。进一步的分析揭示了该地区夏季降水减少主要与印度洋热带赤道地区低层东风加强和高空西风加强有关,亚洲地区中高纬度温度的升高也对该地区夏季降水量显著减少有重要作用。

Based on the observation data from 125 stations in Yunnan Province,the reanalysis data from National Centers for Environmental Prediction/National Center for Atmospheric Research and the monthly extended reconstructed sea surface temperature data from the National Oceanic and Atmospheric Administration in 1960 — 2013,the variation of the Yunnan rainfall and its related atmospheric circulation were analyzed.Major results are as follows：Yunnan rainfall experienced an abrupt decrease in 2002,which is mainly attributed to the notable reduction of Yunnan summer rainfall.Further analyses verified that the prominent decrease in Yunnan summer rainfall seems to be related to the intensified easterly of lower troposphere and strengthened westerly of upper troposphere over tropical Indian Ocean.Besides,the increasing temperature of the Asia continent in middle and high latitudes also play an important role in the abrupt decrease of Yunnan summer rainfall.