2008与1969年冬季持续性雨雪过程对比分析

Analysis of Winter Continuous Snow in 2008 and 1969

利用安徽省降水量资料和NCEP资料对1969年与2008年冬季两次超过半月的持续性雨雪过程进行分析。结果发现:强降水过程之前都有一次阻塞高压较明显增强过程,而强雨雪过程则始于阻塞形势减弱期,当乌拉尔山阻高指数锐减到谷值前后的1～2天,同时伴有偏强的西南气流,会有一次较为明显的降水增强的过程。500hPa环流形势2008年为经向型,冷暖空气均较强,持续性雨雪期间有4次强雨雪天气过程;而1969年环流较为平直,雨雪天气持续较长,但基本无强雨雪过程。通过准双周振荡分析发现1969年持续性雨雪期间的水汽源地主要为南海,2008年水汽则同时来源于南海和孟加拉湾。

Using the data of precipitation and NCEP in Anhui,two continues severe snow processes in 1969 and 2008 are studied,with emphases on the change of the blocking high in the Ural Mountain and the south-west wind over the south of Anhui at 700 hPa.It is found out that before both sever snow processes,the blocking high in the Ural Mountain was strong,and the two snow processes began from the weakening of the blocking high;about 1 or 2 days before or after the index of the blocking high dropping to the lowest,the south-west wind being strong at the same time,the snow enhanced obviously.The quasi-biweekly oscillation of the moisture transport in the south of Anhui at 700h Pa was obvious in January and February in the two years.The water vapor origin of precipitation was from the South China Sea in 1969,and from the Bay of Bengal and the South China Sea in 2008.