Typical Structure,Variety,and Multi-Scale Characteristics of Meiyu Front

作     者：郑永光 陈炯 葛国庆 朱佩君 

作者机构：National Meteorological Center CAPSUniversity of Oklahoma Department of Earth SciencesCollege of ScienceZhejiang University 

出 版 物：《Acta meteorologica Sinica》 (ACTA METEOROLOGICA SINICA)

年 卷 期：2008年第22卷第2期

页      面：187-201页

核心收录：

学科分类：07[理学] 0707[理学-海洋科学] 070601[理学-气象学] 0815[工学-水利工程] 0706[理学-大气科学] 0816[工学-测绘科学与技术] 0824[工学-船舶与海洋工程] 0825[工学-航空宇航科学与技术] 

基　　金：National Major Basic Research 973 Program of China under Grant No.2004CB418300 the National Natural Science Foundation of China under Grant No.40305004 

主　　题：Meiyu front typical structure variety multi-scale 

摘      要：Meiyu front plays an important role in summer rainfall in central China. Based on the GMS-5 satellite images, NCEP reanalyses （2.5°×2.5°） and final analyses （1°×1°） data, and meteorological conventional sounding observations, the horizontal and vertical structures of the Meiyu front were summarized using multiple diagnostic variables, including winds, temperature, jet stream, front, pseduo-equivalent potential temperature, divergence, vertical motion, static instability, etc. In this paper, four cases were selected and analyzed, two of which are in 26-28 June and 23 July 2002 during the Experiment on Heavy Rain in the Meiyu period in the lower reaches of the Yangtze River, and the others are in May and July 1998. The two cases in July 1998 and July 2002 are the secondary Meiyu front cases. The results show that the structures and characteristics of the Meiyu front are different for various cases, or at various places and time, or at various stages of one case, and the frontal characteristics can be converted from the polar front to the equatorial front. Because of the interaction of the different scale circulations in the high and low latitudes, the horizontal structure of the Meiyu front has various forms. The results in this paper also show that the typical Meiyu front consists of a narrow band with a high gradient of potential equivalent temperature below 500 hPa, south of which is warm and moist air mass, and north of which is the transformed air mass from the midlatitude ocean or polar continent. Below the mid troposphere, south of the front blows southwesterlies, while north blows easterlies. The ascending motion and precipitation usually occur ahead of the Meiyu front. In the upper troposphere, the subtropical front is above the Meiyu front, but two fronts are separated. In addition, the upper westerly jet stream and the easterlies to the south of the Meiyu front result in the upper divergent flow field. The multi-scale characteristics of the horizontal