四川省降水相态识别判据研究

Research on Discrimination Criterion of Precipitation Types in Sichuan Province

本文运用1981-2013年四川省156个国家级地面观测站的原始气象记录整编数据,分析了四川省雨、雨夹雪和雪三种降水相态的气候分布特征,并从地面要素和高空要素两个方面详细分析了不同降水相态对应的变量阈值,主要结论如下：（1）降雨日数的第一特征向量近些年呈现出减少趋势,第二特征向量在雅安和广元地区的降水日数有所增加,攀西地区降水日数在减少;从降雪日数的第一特征向量看,四川地区降雪日数近些年也呈现减少趋势,第二特征向量四川中部一线近些年的降雪日数有所增加;雨夹雪日数第一特征向量说明四川大部分地区雨夹雪日数近20年都在减少,阿坝州地区的雨夹雪日数在增加,第二特征向量的趋势并不明显,第三特征向量近15年盆地地区的雨夹雪日数有所增加,川西高原和攀西地区的雨夹雪日数在减少.（2）地面和高空近地层的温度（T）和露点温度（Td）对区分降水相态有较好的指示意义.盆地西部,三种降水相态有较好区分;盆地南部,各要素都能很好的区分雨和雪两种降水相态,但是雨夹雪与雪并不好区分;盆地东北部,只有H700-第一层较容易区分三种不同的降水相态.川西高原上,H500-第一层为区分三种不同降水相态的最佳高空要素;攀西地区,T第一层、T600hPa、零度层高度3 个要素是识别三种不同降水相态的较好指标.

The climatic distribution characteristics of different precipitation types in Sichuan province are analyzed using he meteorological data recorded reorganization from 1981 ~ 2013. And three different precipitation phases of different threshold ranges are summarized from surface and sounding factors. The main results are as follows:( 1) The first eigenvector of rain days' EOF decreases gradually,the second eigenvector of rain days' EOF increases in Ya'an and Guangyuan areas,while the rain day's in Panzhihua also decreases. From the snow days perspective,the first eigenvector shows an decreasing trend of snow days in Sichuan. The second eigenvector shows that the snow days in the middle of Sichuan has slightly increased. The first eigenvector of rain and snow days reflects that the days of rain and snow in most of Sichuan areas are decreasing in recent 20 years,but the ones in Aba are increasing. It is not obvious that the second eigenvector shows. The third one tells us that the days of rain and snow in basin are increasing in recent 15 years,but the ones in west Sichuan plateau and pan-xi region are decreasing.( 2) They are good indicators to distinguish different precipitation types,which are temperature and dew-point temperature in surface and sounding. T850 h Pa is something which distinguishes three different precipitation types in western Sichuan basin. All of the ingredients can distinguish the rain and snow in south Sichuan basin,but it is a difficult thing to make a distinction between snow and 'rain and snow'. H700 ~ first level is something which distinguishes three different precipitation types in northeast Sichuan basin. In west Sichuan plateau,H500 ~ first level is good index to distinguish different precipitation types. In pan-xi region,the good indexes are temperature of first level,T600 h Pa,and the 0℃ level height.