青藏高原春末土壤湿度对初夏降水的影响  

Effect of soil moisture in late spring on precipitation in early summer over the Qinghai-Tibet Plateau

作　　者：央金卓玛 罗布 卓嘎[3,4] YANGJIN Zhuoma;LUO Bu;ZHUO Ga(Weather Modification Center of Tibet Autonomous Region,Lhasa 850000,China;Meteorological Observatory of the Tibetan Autonomous Region,Lhasa 850000,China;Tibet Institute of Plateau Atmospheric and Environmental Science,Lhasa 850000,China;Heavy Rain and Drought-Floods Disasters in Plateau and Basin Key Laboratory of Sichuan Province,Chengdu 610072,China)

机构地区：[1]西藏自治区人工影响天气中心,西藏拉萨850000 [2]西藏自治区气象台,西藏拉萨850000 [3]西藏高原大气环境科学研究所,西藏拉萨850000 [4]高原与盆地暴雨旱涝灾害四川省重点实验室,四川成都610072

出　　处：《大气科学学报》2022年第1期40-50,共11页Transactions of Atmospheric Sciences

基　　金：国家自然科学基金资助项目(41765012);高原与盆地暴雨旱涝灾害四川省重点实验室开放基金项目(SZKT201907);西藏自治区科技厅中央引导地方项目(XZ202001YD0021C)。

摘　　要：为了研究青藏高原(简称高原)春末(5月)土壤湿度与初夏(6月)降水的关系,利用1979—2019年ERA-Interim土壤湿度月平均资料和同时段高原109站观测降水资料,分析了高原春季土壤湿度与汛期(5—9月)降水之间的关系。结果表明:春末表层(0~28 cm)土壤湿度与高原初夏降水呈显著的正相关,在空间上土壤湿度南北反向模态对应高原初夏降水的南北偶极子模态,并且存在两个高相关区域;在此基础上,定义了一个反映春末土壤湿度西北与东南梯度的指数(I_(smg)),发现该指数与6月降水南北反向模态存在明显的负相关,且这种关系从2000年以来更为显著。通过一组I_(smg)加倍的数值敏感性试验,结果得知高原初夏降水正常和偏多年I_(smg)加倍后能够通过增强高原热源,抽吸周边大气向高原中部聚拢,造成高原中部唐古拉山脉一带大气增温增湿、导致降水增加明显,不过这种机制在旱年作用不太明显。In order to study the relationship between soil moisture and summer precipitation on the Qinghai Tibet Plateau in spring,the relationship between soil moisture and summer(May to September)plateau precipitation was analyzed by using era interim soil moisture data from 1979 to 2019 and the observed precipitation data of 109 stations in the same period,which was then verified through a series of sensitivity numerical experiments.The results show that there is a significant positive correlation between surface soil moisture(0-28 cm)in late spring(May)and plateau precipitation in early summer(June).In addition,the North-South reverse mode of soil moisture corresponds to the north-south dipole mode of plateau precipitation in early summer,and there are two high correlation regions.Secondly,an index reflecting the soil moisture gradient at the end of spring is defined.The Smg_Index is the negative correlation between the time series of the first mode of precipitation in June,and this relationship has become more significant since the mid-90s.According to the numerical sensitivity test,after Smg_Index doubled,the surrounding atmosphere converged to the center of the plateau by enhancing the plateau heat source,thereby causing increase of atmospheric temperature and humidity in the Tanggula mountains in the center of the plateau,in turn resulting in an obvious increase of precipitation.However,this mechanism does not play a significant role in dry years.

关 键 词：青藏高原 土壤湿度 初夏降水 土壤湿度梯度指数 敏感性试验 

分 类 号：P461[天文地球—大气科学及气象学]