近五十年中国西北地区夏季降水场变化特征及影响因素分析  

Characteristics and Analysis of Typical Anomalous Summer Rainfall Patterns in Northwest China over the Last 50 Years

作　　者：陈冬冬[1,2] 戴永久[1] 

机构地区：[1]北京师范大学地理学与遥感科学学院/地表过程与资源生态国家重点实验室,北京100875 [2]中国气象局气象探测中心,北京100081

出　　处：《大气科学》2009年第6期1247-1258,共12页Chinese Journal of Atmospheric Sciences

基　　金：国家杰出青年基金40225013

摘　　要：利用中国气象局信息中心提供的西北地区1951～2005年夏季月平均资料集和1958～2002年ERA40资料,分析近五十年来西北地区夏季降水场的主要变化特征,及与之相关的大尺度水汽输送和环流场变化,讨论大尺度环流指数如涛动、极涡、赤道太平洋Ni～no3.4区海温与西北地区夏季降水的相关性。结果表明,近五十年西北西部尤其是南疆的降水增多,与西伯利亚(50°N～60°N,40°E～70°E)上空位势高度增加和伊朗高原(35°N～42.5°N,60°E～75°E)上空位势高度减少有很大关系。1987年后,西北西侧水汽辐合也是该区降水增多的一个重要因素。西北东部降水受海温影响大。此外,北大西洋涛动、极涡面积可以反映近几十年来西北降水西增东减的年际波动。极涡面积大小与西北降水第一模态相关性尤其突出,可以作为考察西北降水变化的一个重要指标。Based on the 1951-2005 monthly rainfall data in Northwest China, which is provide by the Chinese Meteorological Administration Data Center, the authors analyze the spatial and temporal patterns of JJA rainfall in Northwest China. The author try to explain these patterns by using water vapor transport and atmospheric circulation by ERA40 reanalysis data. Results show that the rainfall increase in the west part of Northwest China is highly related to 500-hPa geopotential height changes in Siberia （50°N-60°N, 40°E-70°E） and the Iranian plateau （35°N-42.5°N, 60°E-75°E）. Water vapor convergence is another important factor especially after 1987. The rainfall decrease in the west part of Northwest China can be modified by the sea surface temperature. Atmospheric circulation systems, such as the North Atlantic Oscillation （NAO）, the North Pacific Oscillation, the Nio 3.4 SST, and the vortex area index, are discussed with typical anomalous patterns of summer rainfall. It shows that the NAO and the vortex area have some relations with year-to-year changes of the first EOF mode of rainfall in Northwest China. As the correlation between the first principle component and the vortex area index is high, the vortex area can be used as an indicator to predict the rainfall change in Northwest China.

关 键 词：西北 夏季降水 EOF 水汽输送 大气涛动 极涡 

分 类 号：P426[天文地球—大气科学及气象学]