20世纪70年代末云南省雨季降水的突变及原因分析

Abrupt Change of Precipitation in Rainy Season in Yunnan Province in Late 1970s and its Cause Analysis

利用1961-2011年云南省124个站点的逐月降水资料,NCEP/NCAR大气再分析资料,NOAA全球逐月海温资料,通过M-K突变检验,滑动相关,合成分析等方法分析了云南省雨季(5-10月)月平均降水的突变特征。研究显示:1978年左右云南省雨季降水有一次突变。雨季降水量突变后(1979-2001年)比突变前(1965-1978年)减少,而变化趋势由负转正。突变前后的环流分析表明,蒙古地区反气旋导致的偏北风异常有利于云南省雨季降水突变后比突变前减少,孟加拉湾北部的水汽输送有利于突变后的增加趋势。进一步分析表明,西南印度洋变暖与云南省雨季降水的这一突变相关,其基本影响机制是:西南印度洋变暖,通过海气相互作用,引起低纬环流和中高纬波列变化,从而影响云南雨季降水变化。研究表明,西南印度洋变暖对云南省雨季降水增减的影响存在不确定性。这种不确定性表现为西南印度洋海温距平和云南省雨季降水的滑动相关关系的变化。

Based on the monthly precipitation data of 124 meteorological stations in Yunnan during 1961-2011 and NCEP/NCAR atmospheric reanalysis data,NOAA global monthly SST data,the mutation characteristics of monthly average precipitation in rainy season in Yunnan(May to October） is analyzed by M-K mutation test,sliding correlation and synthetic analysis method.The results are as follows： There is a mutation in the rainy season in Yunnan province in1978.The precipitation in rainy season decreased after the abrupt change(1979-2001） compared with it before mutation(1965-1978）,while the change trend is from negative to positive.The circulation analysis has shown that the abnormal northerly winds caused by anticyclone in Mongolia area is beneficial to the decrease of precipitation after the abrupt changing compared with it before mutation.While the increased water vapor transport of northern Bay of Bengal makes a contribution to the increasing trend in rainy season precipitation in Yunnan after the mutation.Further analysis has shown that warming in the southwest Indian Ocean is related to the mutation in rainy season rainfall in Yunnan,and the basic influence mechanism of which is as follows： warming in the southwest Indian Ocean,through air sea interaction,leads to the low latitude and high latitude wave changing,and thus affects rainy season precipitation in Yunnan.And study shows that warming in the southwest Indian Ocean has an unsure influence on the change of rainy season precipitation in Yunnan.This uncertainty is manifested as the change of the sliding correlation between SWIO and rainy season precipitation in Yunnan.