东北地区春季首场透雨的变化特征及与青藏高原地面加热场强度的关系

Characteristics of the First Soaking Rain in Northeast China and Its Response to Surface Heat Source over the Tibetan Plateau

利用1958—2012年4—5月东北地区（39°-55°N、118°-135°E）101个站点逐日降水资料、青藏高原地区（25°-40°N、73.75°-103.75°E）JRA-55的地面感热和潜热通量月平均再分析资料以及NCEP/NCAR-I大气环流场的月平均再分析资料,分析了春播期首场透雨出现日期的时空变化特征及其与透雨量和播种期降水量间的关系,以及对青藏高原地面加热场强度异常的响应及其可能机制。结果表明：透雨日期自1958年以来在东北地区的西北和东南大部分区域呈现略微偏晚的趋势;中部有略微偏早的趋势。春播期首场透雨出现时间偏早（晚）的地方,首场透雨量小（大）,春播期总降水量多（少）。同时,4月青藏高原地面加热场强度增强（减弱）,有利于（不利于）来自北方的冷空气和南方的暖湿气流在东北上空交汇,且上升气流增强（减弱）,水汽输送充沛（减少）,导致该地区春季首场透雨出现的时间偏早（晚）。

Based on the precipitation data in April and May for the period 1958 — 2012 from 178 meteorological stations in Northeast China,JRA-55 and NCEP/NCAR-I reanalysis,the study is performed of the first soaking rain date as well as its relation with the soaking rainfall and the total rainfall from April to May.In addition,response of the soaking rain date to the surface heat source over the Tibetan Plateau is also discussed.The results suggest that,since 1958,the soaking rain date in Northeast China,has shown a positive relation with the soaking rainfall and a negative relation with the total rainfall,suggestive of the place where the soaking rain date is early（late）,the soaking rainfall is smaller（larger） and the total rainfall is larger（smaller）.Besides,the correlation between the surface heat source over the Tibetan Plateau in April and the soaking rain date is negative,which means when the surface heat source in April gets enhanced,cold air from the north and warm air from the south intersect over Northeast China,updrafts,are strengthened,and water vapor transport is abundant,making the soaking rain date in Northeast China come early（late）.