2009年3月中旬新疆融雪型洪水气象成因分析

The Possible Weather Causes for Snowmelt Flooding in Xinjiang in Mid-March 2009

利用1950—2006年的新疆融雪型洪水灾情资料对新疆地区融雪型洪水发生特点进行了分析。结果表明:新疆地区融雪型洪水多发生在天山北坡,特别是伊犁河谷和塔城地区是融雪型洪水的多发区域。3月中旬到4月上旬为融雪型洪水的多发时期。在此基础上,从气候背景、天气诊断分析等方面对2009年3月中旬融雪型洪水的气象成因进行了分析和研究,得出:2009年2月降水明显偏多为3月中旬融雪洪水的发生提供了基础条件,而3月中旬冷空气过后气温持续迅速回升是此次融雪洪水发生的主要气象因素。持续迅速升温过程中,平均气温由负转正、最高气温高于5℃以及暖平流中心出现时间对融雪型洪水预报具有指示意义。

Using the snowmelt flooding disaster data from 1950 to 2006,snowmelt flooding characteristics of the Xinjiang region were analyzed.The results indicate that snowmelt flooding over Xinjiang region usually occurred in the northern slope of Tianshan Mountains,especially in the Ili River Valley and Tacheng area,while snowmelt flooding most easily occurred for the time from mid-March to early April.On the basis of it,climate background,weather process,diagnostic analysis were analyzed on the possible weather causes for snowmelt flooding occurring in mid-March 2009.Finally we can see the basic condition for snowmelt flooding occurrence that the rainfall in February 2009 was obviously more than the average value in the same period of the past years,and air temperature rapidly and continually increased after the cold air passing through,all these may be the most possible causes for the snowmelt flooding in mid-March 2009. During the durative and rapid heating process,the time for mean temperature being higher than 0℃,the highest temperature being higher than 5℃as well as warm advection center appearing has the instructive significance to snowmelt flooding forecasting.