摘要:西北太平洋副热带高压（以下简称副高）是影响中国气候的大尺度环流系统，研究次季节尺度副高东西变动对西南地区降水的影响具有十分重要的意义。本文首先根据副高东西变动的关键区位置分别定义了前夏和后夏副高东西变动指数，指数具有显著的10～30天次季节周期，能够很好表征副高次季节东西变动的特征。根据指数的标准化值，共选取前夏和后夏东西事件195次（1374天）。进一步对东西事件的分析表明次季节尺度上副高东西变动与西南地区降水有十分密切的联系，在副高偏西（东）事件中，副高经历了由东→西→东（西→东→西）逐渐变化的过程，相应西南大部分地区的降水经历了逐渐由少→多→少（多→少→多）的演变，次季节尺度上西南地区降水对副高变化的响应与副高东西变动过程中副高北侧及副高主体区域的水汽和气流的垂直变化有很大的关系。另外，分析发现对于西南地区而言，受副高次季节东西变动的影响，贵州和重庆地区降水变化的一致性比较好，而云南和四川地区降水变化的区域差异较大，尤其是云南。前夏，在副高东西变动过程中云南大部分地区的降水呈现出与西南大部分地区，尤其与贵州和重庆地区的降水变化完全相反的特征，即副高偏西（东）事件中，云南大部分地区的降水偏少（多），西南其它大部地区降水偏多（少）；后夏，除云南中北部地区，西南大部分地区的降水变化基本一致。
关键词:次季节尺度/
西太平洋副热带高压东西变动/
前夏和后夏/
中国西南地区/
夏季降水
Abstract:Western Pacific subtropical high (WPSH) is a large-scale circulation system that affects climate change in China. It is of great significance to study the influence of the subseasonal WPSH east–west movement on the precipitation anomalies in Southwest China. In this study, the WPSH east–west displacement index is first defined according to the main activity region of the WPSH in early and late summers. The index has a significant period of 10–30 d and can well indicate the WPSH zonal movement. A total of 195 east and west WPSH events (1374 d) are chosen based on the standardization index. The results show that the subseasonal WPSH zonal movement is closely related to the precipitation in Southwest China. During the west (east) events, the WPSH moves gradually as follows: east→west→east (west→east→west), and the rainfall in most of Southwest China changes as follows: less→more→less (more→less→more). The precipitation variation in Southwest China is closed related to the anomalous water vapor and atmospheric vertical movement in the northern side and main WPSH area. Furthermore, the results show that the precipitation anomalies in Guizhou and Chongqing are well coincident, which demonstrates the significant characteristics of the regional difference in Yunnan and Sichuan during the subseasonal WPSH movement, especially in Yunnan. In early summer, the precipitation anomalies in Yunnan are contrary to those in most of Southwest China, especially in Guizhou and Chongqing. For example, when the WPSH moves westward (eastward), the precipitation is less (more) in most of Yunnan; on the contrary, the precipitation in most regions of Southwest China is more (less). In the late summer, except the central and northern Yunnan, the precipitation anomalies in most of Southwest China are basically accordant.
Key words:Subseasonal scale/
WPSH east–west movement/
Early and late summer/
Southwest China/
Summer rainfall
PDF全文下载地址:
http://www.iapjournals.ac.cn/dqkx/article/exportPdf?id=5cebbdd6-7395-4770-a351-cb52c4c0b13a
