徐州市2010年秋冬连旱成因分析与探讨

Analysis and Discussion on the Causes of Consecutive Drought in Autumn and Winter in Xuzhou in 2010

2010年徐州地区发生了1950年以来最为严重的秋冬连旱,连续5个多月的降水量偏少90%,依据GB气象干旱等级,达到了特旱级别。干旱严重影响了小麦播种和出苗,对小麦的生长和越冬造成了严重危害。根据详实的资料,分析了该次干旱的3个主要成因:①La Nina事件在干旱中伴有主要角色;②秋冬季特殊的环流特征及其异常的演变阻碍了低纬度海面上的水汽向北方陆地输送,秋季盛行高指数环流,不利于冷空气南下,冬季的纬向环流指数异常偏低,有利于强冷空气频繁爆发南下,导致了秋季干热和冬季干冷即秋冬连旱;③降水量分布极端的不均匀也是秋冬连旱的重要原因之一。上述3个成因可作为今后干旱预测的着眼点和预测因子加以利用。

Since 1950s,the most severe consecutive droughts in autumn and winter occurred in Xuzhou in 2010,precipitation of continuous five months reduced 90%,based on GB meteorological drought level,reached serious drought level.The effect of serious drought on seeding and emergence of wheat was serious,which generated serious harm on the growth and overwintering of wheat.According to detailed data,three main reasons of this drought were analyzed： ① La Nina accident played main characters in drought;② the unique circulation characteristics of autumn and winter and its abnormal evolution blocked the transport of water vapour from the low latitude sea surface to land of north,there was high index circulation in autumn,which was not beneficial for the cold air down south,zonal circulation index of winter was lower extraordinarily,which was favorable for the cold air down to the south frequently,resulted in dry and hot autumn,and cold and dry winter.③The heterogeneous precipitation was one of the main reasons.The 3 causes mentioned above can be applied in prediction of drought.