青藏高原春末土壤湿度对初夏降水的影响

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...

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

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.