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对2009年德阳初夏严重干旱及其成因进行分析。结果表明:导致德阳严重夏旱的主要原因是5～6月亚洲中纬度地区环流平直,极涡偏于西半球,导致影响我国的冷空气势力偏北偏弱。南海夏季风爆发较多年平均时间偏晚,导致副热带高压脊线偏南,西伸点偏东,使中纬度地区平直西风带上的小波动无阻塞,快速东移。印度夏季风建立虽然较多年平均偏早,但强度偏弱,位置偏南,不利水汽向北输送。印缅槽位置偏南,不利于将孟加拉湾等地的暖湿气流带到四川。致使四川德阳降水严重偏少,从而出现严重夏旱。
The severe drought in early summer of Deyang in 2009 and its causes were analyzed. The results show that the main reason leading to severe summer droughts in Deyang is the flat circulation in mid-latitudes from May to June, with the polar vortex deviating to the western hemisphere, causing the cold air forces affecting our country to be slightly northerly weaker. The onset of the SCS summer monsoon averages more years than average, resulting in the subtropical high ridge moving southwards and the westward extending point eastward, making the small fluctuation in the flat westerly zone in the mid-latitude region non-blocking and moving eastward rapidly. Although the establishment of the Indian summer monsoon is relatively earlier than normal for many years, its intensity is weaker and its location is slightly southward, which hinders the transmission of moisture to the north. India and Myanmar slot south, is not conducive to the Bay of Bengal and other warm and humid air flow to Sichuan. As a result, the precipitation in Deyang, Sichuan Province was seriously under-normalized, resulting in severe summer drought.