1961—2019年青藏高原中东部夏季强降水与大尺度环流的关系

采用一元线性回归、合成分析等方法对1961—2019年青藏高原中东部71个站点夏季强降水与大尺度环流进行了分析，研究结果表明，近年来青藏高原中东部强降水呈增加趋势。在强降水高值年时，青藏高原中东部水汽辐合加强，中纬度西风和热带地区东风带向极移动加强，高层辐散流场、水汽输送以及上升运动条件，共同作用导致了强降水的产生。在强降水低值年时，青藏高原中东部大部水汽异常辐散，区域内的季风水汽输送减弱，西风带和东风带均向赤道移动减弱，高层为气旋式环流异常。通过风暴轴、波作用通量和E-P通量进一步分析发现，当北大西洋地区风暴轴偏强（偏弱）时，瞬变扰动作用加强（减弱），使得北大西洋地区高纬度西风加速（减弱），急流出口区的不稳定能量激发了欧洲西北部的异常反气旋（异常气旋），并通过Rossby波列调控季风输送，导致了青藏高原中东部地区强降水的变化。

Relationship between the summer extreme precipitation in the Qinghai-Tibet Plateau and large-scale circulations from 1961 to 2019

Based on the analysis of the index of very wet day precipitation （R95p） at 71 stations in the central and eastern part of the Qinghai-Tibet Plateau， unvariate linear regression and synthetic analysis were used to conclude the result： the R95p is increasing in recent years. In high value years of R95p， the poleward movement of the westerly in the middle latitude and easterly in the tropical region are strengthened. Meanwhile， the moisture transport of the south Asian monsoon increased and enhanced at the south of the Qinghai-Tibet Plateau with upper layer abnormal anticyclonic circulation， abundant water vapor and strong updraft together caused the convergence of water vapor strengthened in the eastern parts of the Qinghai-Tibet Plateau. In high value years of R95p， vice versa. Through further discussion and analysis， we have obtained a mechanism that can influence the R95p changes on the Qinghai-Tibet Plateau： When the storm track in the North Atlantic region intensifies， the forcing effect of the transient eddy on the basic airflow is strengthened which accelerated the mid and high latitudes westerly. Furthermore， the instability energy in the exit of the North Atlantic jet generated an anomalous high pressure in northwestern Europe， which in turn affected the monsoon systems through the Rossby wave train. Finally， regulated the R95p in the central and eastern parts of the Qinghai-Tibet Plateau. Research on the relationship between the R95p and large-scale circulation on the Qinghai-Tibet Plateau can provide a certain reference for long-term forecasting.