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利用1979～2010年NCEP全球逐月的2.5°×2.5°再分析资料,从降雨量、温度、地理、大气环流、厄尔尼诺现象等方面,分析了2009～2010年干旱的时空分布及其同期的大气环流异常特征,探讨此期间干旱的成因。结果表明,2009年11月～2010年5月上旬昭通市出现有气象记录以来最严重的秋冬春特大连旱,2010年1～4月,昭通市降水量与常年同期相比,减少9.0%～74.3%,各站降水量在26.5～215.0 mm,50.0～100.0 mm的站有10个,50.0 mm以下的站有10个,与此同时,自2009年6月以来,赤道中东太平洋海温持续异常偏高,进入厄尔尼诺状态。这次干旱主要是由于厄尔尼诺事件导致大气环流异常,500 hPa贝加尔湖低压较常年异常偏强,我国北方地区冷空气较强,但我国南方大部地区环流较为平直,位势高度也较常年偏高,而西太平洋副热带高压较常年偏西偏强,印度季风偏弱,印度洋的水汽不能向我国西南地区输送,导致降水偏少,从而导致干旱。
Based on the global monthly NCEP 2.5 ° × 2.5 ° reanalysis data from 1979 to 2010, the spatial and temporal distribution of the drought from 2009 to 2010 and its atmosphere in the same period were analyzed from the aspects of rainfall, temperature, geography, general circulation and El Niño phenomenon Abnormal characteristics of circulation, to explore the cause of drought during this period. The results showed that in the period from November 2009 to early May 2010, the autumn and winter spring drought in Dalian, Zhaotong City, recorded the most severe autumn drought. From January to April 2010, the precipitation in Zhaotong City decreased by 9.0% ~ 74.3%. There are 10 stations with precipitation of 26.5-215.0 mm and 50.0-100.0 mm at each station and 10 stations under 50.0 mm. At the same time, the SST in the equatorial Pacific Ocean continued to be abnormal since June 2009 High, into the El Niño state. The drought was mainly due to the atmospheric circulation anomaly caused by the El Niño event. The low pressure of Baikal Lake at 500 hPa was anomalously stronger than that of normal years. Cold air in northern China was stronger. However, the circulation in most parts of southern China was relatively flat and the geopotential height was also higher than that of normal years However, the western Pacific subtropical high is stronger than that of normal years, and the Indian monsoon is weak. The Indian Ocean moisture can not be transported to the southwest of our country, resulting in less rainfall and leading to drought.