降水作用会导致冻土活动层的水热状态发生明显变化， 并且青藏高原地区的降水也表现出明显的季节性差异。为了分析季节降雨特征对冻土活动层内部水热状态的影响效果， 对青藏高原中部北麓河地区的气象资料以及活动层内部的热通量、 含水量、 温度变化开展了原位监测。研究结果表明： 北麓河地区是以小雨事件为主， 中雨事件为辅的降雨特征， 小雨事件占3 -11月降雨事件的90%左右。并且， 夏季还会发生大雨事件， 秋季出现持续降雨事件。其中， 各个季节降雨事件导致地表净辐射整体呈现减小的趋势， 且夏季大雨事件对净辐射的影响效果更加明显， 秋季持续降雨事件导致净辐射表现出先增加后减小的趋势， 土壤热通量的变化规律与净辐射的变化基本一致。降雨作用通过影响地表净辐射改变了土壤热通量的变化， 进而引起土壤内部水分场及温度场发生改变。其中， 夏季大雨及中雨事件会显著增加浅层土壤含水量， 而春季和秋季降雨对土壤含水量影响较小； 各个季节小雨事件对土壤温度的影响可以忽略， 但中雨、 大雨及持续降雨事件会显著缓解浅层土壤升温趋势， 且随着深度增加， 降雨事件对于缓解土壤升温趋势逐渐减弱。研究结果对于多年冻土区的区域生态环境问题以及工程建筑物病害防治问题的解决具有一定的指导意义。

Rainfall can cause significant changes in the hydrothermal state within the active layer of the permafrost regions， and the rainfall in the Qinghai-Xizang （Tibet） Plateau has obvious seasonal characteristics.In order to analyze the effects of seasonal rainfall characteristics on the hydrothermal state of permafrost active layer， the meteorological data and the changes of soil heat flux， water content， and temperature within the active layer were monitored in the Beiluhe area of the central Qinghai-Xizang （Tibet） Plateau.The results show that the Beiluhe area is mainly characterized by the light rain events， supplemented by the moderate rain events， and the light rain events accounted for about 90% of the rainfall events from March to November.In addition， the heavy rain events and sustained rain events occur in summer and autumn， respectively.Among them， the rainfall events in each season leads to an overall decrease in surface net radiation， and the impact of the heavy rain events on the net radiation in summer is more obvious.The sustained rain events in autumn lead to a trend of first increase and then decrease in net radiation， and the change trend of soil heat flux consistent with changes in net radiation.Rainfall changes the soil heat flux by affecting the surface net radiation， thus causing changes in the water field and temperature field within soil.Among them， the heavy and moderate rain events in summer can significantly increase shallow soil water content， while spring and autumn rainfall have little effect on soil water content.The effect of the light rain events on soil temperature in each season can be ignored， but the moderate rain， heavy rain and sustained rain events can significantly alleviate the warming trend of shallow soil， and the effect of the rainfall events on alleviating soil warming gradually weakened with the increase of depth.The research results have certain guiding significance for solving regional ecological environment problems and engineering building disease prevention and control problems in permafrost regions.