中文摘要：

青藏高原冬、春积雪有着显著的南、北空间差异,本文利用通用地球系统模式（CESM）设计了增加高原南、北冬、春积雪的敏感性试验,结果表明：当高原南部冬、春积雪异常偏多,长江及其以北地区夏季降水偏多,华南大部分地区夏季降水偏少;而当高原北部冬、春积雪异常偏多,华北及东北地区夏季降水偏多,长江下游南部地区夏季降水偏少,雨带更偏北。青藏高原南、北部冬、春积雪异常影响中国东部夏季降水的物理机制的分析结果表明,高原不同区域（南部和北部）冬、春积雪异常引起的非绝热加热异常效应都可持续到夏季,且北部积雪异常持续时间更长。高原南部和北部积雪异常偏多均会减弱高原北侧上空大气的水平温度梯度,进而减弱高原北侧西风急流的位置及强度,进而影响下游出口区处急流的强度和位置,且高原北部积雪异常偏多的影响更大。当高原南部积雪异常偏多,急流出口区的西风急流加强且偏南;而高原北部积雪异常偏多,出口区的西风急流减弱且偏北。相应地,对流层中层500 h Pa西太平洋副热带高压减弱,低层850 h Pa异常反气旋环流,影响中国东部地区水汽输送,从而影响了中国东部地区夏季雨带的变化。当高原南部积雪异常偏多,异常反气旋性环流位于东海附近,有利于更多水汽输送至长江流域,华南水汽输送减少;当高原北部积雪异常偏多,异常反气旋性环流相对偏北,更有利于华北及东北水汽输送,雨带偏北。

英文摘要：

This study investigates the relationship between the spring–winter snow cover anomalies over the northern and southern Tibetan Plateau（TP） and summer precipitation in East China（EC） based on numerical experiments ofCESM（Community Earth System Model）.The results show that snow cover anomalies over the southern and northern TP can lead to two patterns of summer precipitation in EC.Larger snow cover in the southern TP leads to excessive rainfall in the Yangtze River basin and northeastern China and less precipitation in southern China; larger snow cover in the northern TP results in enhanced rainfall in northern and northeastern China and less rainfall in the south of the lower reaches of Yangtze River.The possible mechanism of the impacts of snow cover anomalies in the northern and southern TP on summer precipitation in EC is that,changes in the diabatic heating over TP in the summer caused by snow cover anomalies results in weakened temperature gradient and westerly jet on the northern side of TP,and subsequent anomaly of westerly in the exit region.These anomalies further influence the West Pacific Subtropical High（WPSH） in the mid-troposphere and lead to anomalous anticyclonic circulation over EC.Heavier snow cover in the southern TP leads to enhanced westerly jet in the exit region,while heavier snow cover in northern TP results in weakened westerly jet.The degree of the WPSH weakening caused by larger snow cover in the northern TP is greater than that caused by the larger snow cover in southern TP.Thereby the anomalous anticyclonic circulation is located more northward.As a result,the summer rainfall belt shifts northward.