青藏高原雪盖异常的环流特征及其与我国夏季降水的关系

在1955~1993年各种类型青藏高原冬季积雪资料进行综合再分析基础上, 通过典型年份合成对比与相关分析, 发现青藏高原冬季雪盖异常, 同期北半球中高纬500 hPa高度场存在3正2负遥相关结构及相似二维Rossby遥相关波列, 该遥相关型强度指数I_asp与夏季大气环流又存在一个明显的东亚—太平洋遥相关的关系, 与长江中下游汛期旱涝呈正相关, 最高相关区位于江南北部。遥相关强度指数I_asp的强弱在较大程度上间接反映高原积雪异常与否, 并为积雪因子在我国汛期旱涝预测的应用提供一定的物理基础。

A Circulation Signal of Abnormal Snow Cover over the Tibetan Plateau and its Relation to Summer Rainfall in China

Based on the integrated analysis for 1955-1993 snow cover data on the Tibetan Plateau and the NCEP/NCAR reanalysed Northern Hemisphere 500 hPa geopotential height data, comparison and correlation analysis were performed. It is revealed that there is a atmospheric teleconnection pattern during snowcover anomaly over the Plateau in winter, so abnormal snowcover teleconnection pattern intensity index (I asp ) is given. Results further reveal the possible association with East Asia-Pacific summer teleconnection patter and its impact on the rainy season rainbelt distribution in China, especially on the rainfall over the middle and lower reaches of Yangtze River Valley. The result provides a physical base for the application of I asp in short-term climate prediction.