中文摘要：

利用陕西82个气象观测站的降水观测资料、NCEP/NCAR的2.5°×2.5°再分析资料以及MODIS卫星的气溶胶产品,分析了1960-2012年陕西雨季和全年的降水量、降水日数变化特征,并讨论了大气可降水量和气溶胶对降水的可能影响。结果表明,近60年陕西雨季、全年雨量和降雨日数均呈南多北少分布,年总雨量和降雨日数均呈下降趋势,雨季总雨量呈增加趋势,而降雨日数呈降低趋势,雨季雨强增加,降水向雨季集中;陕西全年和雨季小雨雨量和降雨日数均呈现下降趋势,雨季10 mm以上的降水量和降雨日数均呈增加趋势,增加站点占所选站点的75.6%,雨季降水的增加主要是10 mm以上降水量的贡献。陕西全年总雨量的减少可能与整层大气可降水量的减少有关。全年和雨季5 mm以下降水量的减少应该与气溶胶对降水的抑制有关,雨季10 mm以上降水量增加与气溶胶对降水的促进作用有关。分析表明当AOD≥0.4时,雨季气溶胶对降水有一定的促进作用。总之,陕西全年小雨的减少以及雨季10 mm以上降水量增多,雨量向雨季集中应该与近几十年陕西气溶胶增加、气溶胶类型的转变有较大关系。

英文摘要：

Based on observational data（82 meteorological stations）of rain frequency and amount from 1960 to 2012,the variation of total rainfall and frequency of annual and rain season（from June to September）during1960-2012 were analyzed.And the variation of atmospheric perceptible water over Shaanxi,the effect of aerosol on precipitation was also discussed based on NCEP/NCAR reanalysis data（2.5°×2.5°）and MODIS C05 aerosol product.The result shows that the trend of annual rainfall and annual rain frequency decreased,while in rain seasons,there was an increase of total rainfall and a decrease of rain frequency.This phenomenon indicated thatrainfall intensity was enhanced and rainfalls highly concentrate in rain season.For annual and rain season,thelight rainfall and rain frequencywas slightly dropped.Whilein rain season,theamount and frequencyof moderate and heavy rain（≥10mm）was obviously increased（about 75.6% to total observation station）.The variation of atmospheric perceptible water over Shaanxi provinceindicatedthatthe drop of annual rainfall may great related with the decrease of atmospheric perceptible water from 1960 to 2012,but opposite to the rainfall increasein rain season.Furthermore,the variation of aerosol optical depth（AOD） showed that there was a heavy aerosol loading and increasing tendency in AOD over Guanzhong,Hanzhong and Ankangbasin of Shaanxi province because of human activities during the last few decades,just the same regions of increase of rainfall in rain seasons.And the main aerosol type gradually shifted to the urban industrial type in Shaanxi.Studies showed that in some conditions high AOD may favor the precipitation.Therelationship of AOD and rainfall variabilityin Rain seasons showed that in Shaanxiprovince when AOD≥0.4 and rainfall≥10mm,the increased of AOD will invigorate the rain events.In general,the increase of rain events and rainfall concentrate in rain season was highly related with the increase of AOD over Shaanxi province.