云南2009～2010年秋冬春连旱成因分析

2009年秋季至2010年春季,云南降水量比常年同期偏少50%～78%,创有记录以来最少,气温比常年同期偏高0.9～2.5℃,发生了百年不遇的秋、冬、春连旱。分析其发生的原因主要是：2009年秋季开始,西太平洋副热带高压偏强,阻断了从孟湾和南海到云南的水汽输送,加之东亚大槽偏弱偏北、亚洲极涡偏弱,导致冷暖空气不能在云南上空＂相遇＂,造成降水偏少。2009年6月开始El Nino事件开始显现,冬季达到旺盛期,在其影响下,南海、中南半岛到西印度洋的对流活动受到抑制,造成输送至云南的水汽偏弱。全球气候变暖使各种气象要素的变化偏离了平均值,容易引发极端气候事件,导致近年来干旱发生的频率增多增强。

CAUSE ANALYSIS OF DROUGHT FROM AUTUMN 2009 TO SPRING 2010 IN YUNNAN PROVINCE

From autumn 2009 to spring 2010,the precipitation in Yunnan was 50%～78% less than normal year,which is the least ever records,and the temperature was 0.9～2.5℃ higher than normal year.A once-in-a-hundred-year autumn-to-spring continuous drought happened.After analysis,the main causes are,from autumn 2009,the west pacific subtropical high became strong,blocked the water vapor transport from Bay of Bengal and South China Sea to Yunnan,and together with the East Asian Trough was weak and further north,Asian polar vortex was weak.All of the reasons above leaded to the cold and worm air could not ＂encounter＂ over Yunnan,and then caused less precipitation.El Nio event began to appear in June 2009,and became strongest in winter,under the influence of it,the convective activities over South China Sea,Indo-China Peninsula to West Indian Ocean were inhibited,and caused the water vapor transport to Yunnan being weak.Global warming causes the change of various meteorological elements deviating from the average,which makes the extreme climate events happen easily,and leads to the drought becoming more frequently and stronger.