摘要
利用GOES-9红外云图和NCEP／NCAR1°×1°再分析资料，分析了2003年6月29日～7月12日长江中下游一次典型梅雨期间暴雨系统的云系成员及其相互作用。结果表明：（1）梅雨暴雨系统的云系成员主要有四个，它们是梅雨锋云系、西风带短波槽云系、青藏高原东移扰动云系和季风云涌。这些云系成员都可以影响到梅雨锋云系的形状和强度，对梅雨锋云系的建立或重建都起到重要的作用。（2）梅雨云系成员是相应的天气系统相互作用的产物，副热带高压决定梅雨锋云系的位置，因此也决定了暴雨发生的区域。适当强度的高空槽可以诱生梅雨气旋，产生锋面气旋暴雨。高原东移扰动云系如果受高原槽的引导可以移出高原，同时也诱生西南低涡并移出四川盆地，高空槽和低涡共同作用造成了沿途暴雨。季风云涌在副高东退的情况下，就有可能北上和梅雨锋云系连在一起。不同的云系成员和梅雨锋云系相互作用的结果形成不同的云系分布。
The summer monsoon rainfall over East Asia is identified as Meiyu, and it usually lasts for 2 - 3 weeks in the mid - lower reaches of the Yangtze River during June and July. During the typical Meiyu period, it is found that heavy rainfall has close relations with activities of some weather systems, for instance, the four synoptic systems of the western Pacific subtropical anticyclone, the monsoon surges, the northerly cold air and the northeastern plateau trough. Synoptic studies demonstrate when these four main synoptic systems are in the stage of ＂phase lock＂ （which means their relative position, coverage and intensity are less change）, the Meiyu frontal rain zone often maintains and heavy rainfall occurs. However, what kind of cloud systems are corresponding to the synoptic systems, and how they interact to affect the Meiyu heavy rainfall are still unclear. The features of Meiyu cloud systems and their activities are studied in this paper. Base on satellite observation, the GOES-9 infrared images, Black Body Temperature （TBB） and the NCEP/NCAR 1°×1° reanalysis data are used to show the heavy rainfall cloud systems＇ formations, evolutions and interactions in the typical Meiyu period from 29 June to 12 July 2003. Results show that the main cloud systems of heavy rainfall in the typical Meiyu period are （i） the Meiyu frontal cloud system, （ii） the westerly short wave trough cloud system, （iii） the eastern Tibetan Plateau eastward-traveling disturbance and （iv） the monsoon cloud cluster, and their interactions are propitious to Meiyu frontal rainfall. The interactions among these four cloud systems are important for the Meiyu frontal cloud zone＇s construction/reconstruction to form a specific cloud pattern with corresponding intensity. Each cloud system relies on synoptic systems and their interactions, i. e., the subtropical high affects the position of the Meiyu cloud system, so the region of heavy rainfall is determined, and the westerly short wave and monsoon cloud cluster act on the Meiyu frontal cloud system resulting in different intense rainfall and orientations. During the period of two weeks, the mid-level short wave trough cloud system induces a cyclone in the Meiyu front to produce heavy rainfall when it moves eastward, which depicts clearly a meso-α-scale vortical cloud cluster embedding in the belt-like synoptic Meiyu frontal cloud system. Although many studies stress that the convective cloud systems seldom move eastward from the Tibetan Plateau, when leaded by the traveling short wave trough, the cloud system in the eastern Tibetan Plateau could move away, hence the low level south-west cyclone （SWC） from the Sichuan Basin follows, and SWC is known as heavy rainfall producer on the way in summer monsoon period. The monsoon cloud clusters do not often go across the east foot of the Tibetan Plateau to the lower reaches of the Yangtze River basin, but they could touch the Meiyu cloud system with heavy rainfall accompanying whenever the subtropical high retreating eastward. In fact, the typical Meiyu frontal cloud system lasts a few days with pattern＇s change and cloud growth/decay. The four cloud systems and their interactions are helpful for elongating from west to east narrow Meiyu frontal cloud system which produces heavy rainfall.
出处
《大气科学》
CSCD
北大核心
2006年第4期578-586,共9页
Chinese Journal of Atmospheric Sciences
基金
国家重点基础研究发展规划项目G1998040910
关键词
梅雨
卫星云图
云系成员
Meiyu/Baiu, satellite image, cloud families
