青海东部—甘肃中部降水类型和干旱形势的变化趋势

The Trends of Precipitation Types and Drought in the Region from Eastern Qinghai to Middle Gansu

利用青海东部—甘肃中部14个气象站点1962-2010年降水观测资料结合NCEP-CFSR（National Centers for Environmental Prediction,Climate Forecast System Reanalysis）再分析资料,分季节、分类型研究了该地区降水与干旱的关系以及变化趋势。结果表明,所研究区域在2001年之前,除了秋季以外,其他季节整体干旱形势呈现出下降趋势,2001年以后只有夏季干旱形势有所加重,但其他季节干旱形势总体下降;对于不同类型降水,1962-2010年整个区域的降水主要以小雨为主,但随着年代的推移小雨对总降水的贡献逐渐下降,中雨的贡献量则有所上升,大雨贡献量在20世纪80年代以后也有增加的趋势;这一地区多年降水量以2001年为界有先减后增的趋势,在2001年以后对这一地区干旱形势影响较大的雨型有从小雨向中雨转变的趋势。

Using NCEP-CFSR（ National Centers for Environmental Prediction, Climate Forecast System Reanalysis） reanalysis data and the data of precipitation from 1962 to 2010, seasonal trends of different rain types were examined. It was found that there was a downward trend of drought in different seasons except autumn. Then after 2001 ,the drought in summer tend to be more serious but others＇were still going to low level. At the same time,it was found that small rain plays the most important role in all types of precipitation. In the 49 years,the proportion of small rain was going to low level with other two types of precipitation are going to high level. 2001 is a dividing line,the total number of precipitation were increased after decreasing. And the moderate rain becomes more important.