利用FY2E卫星降水资料对西藏地区降水日变化特征分析

The Characteristics of Diurnal Variations of Precipitation Analysis in Tibet Accord to FY2E Precipitation

为揭示西藏地区5～9月降水日变化,利用FY2E降水产品和西藏150个自动站降水资料,采取统计和谐波分析方法研究西藏地区降水日变化。结果表明：FY2E降水资料能很好地反映西藏降水量的相对强弱和大致过程;降水量依赖于短时强降水,而不是靠降水次数;降水量有明显的日变化,在当地时间傍晚前后降水量达到峰值;降水频率在一天中则有多个峰值,日变化不明显;自动站表明西藏降水也有明显的日变化,与卫星资料峰值时间误差主要是由于西藏东南地区和樟木沿线降水量远大于其他地区造成的;降水量谐波分析表明西藏地区的降水日变化非常显著;无论是降水量还降水频率,西藏全区表现出明显的夜雨特征,在日喀则东北至拉萨为西藏地区的夜雨中心。

To reveal the rainfall diurnal variation in the Tibetan area from May to September, according to FY2E hourly precipitation products and 150 Tibet regional automatic stations, adopt to study the diurnal precipitation in Tibet. The results showed that： FY2E precipitation data can well reflect the relative strength of Tibet area rainfall and general process. Precipitation depend on the short-time strong rainfall, rather than the precipitation frequency. The precipitation show Tibetan areas ha obvious diurnal variation, around the local time about in the evening before and after the ainfall peak. The precipitation frequency ha more than one peak in a day and its diurnal is not obvious. The regional automatic stations also show that precipitation ha obvious diurnal variation in Tibet, The error of peak time mainly due to the pre- cipitation in south-east and south Tibet is greater than in other regions. The harmonic analysis show remarkable daily variability in Tibet＇ s precipitation. Both precipitation and precipitation frequency show significant night-rain, the Xigaze to northeast Lhasa in Tibet the night-rain center.