2013年6月26—29日江西梅雨锋暴雨天气过程分析

利用实况资料和NECP再分析资料,对2013年6月26—29日江西连续暴雨天气过程进行天气学分析。结果表明,在典型的梅雨环流背景条件下,南亚高压,副高和西南季风的爆发,加之高空低槽和中低层持续性切变等系统共同配合造成了此次暴雨过程。此次过程水汽条件充沛,有2条明显的水汽输送通道:一条从孟加拉湾由西南季风分别通过云贵高原和中南半岛北部输送至副高西北侧;另一条从南海西北部由副高西侧的偏南气流向北输送。两股水汽在副高西北侧汇合加强并沿副高边缘向江南上空输送。西南季风是此次梅雨锋暴雨的关键因素,一方面有利于水汽的输送,另一方面触发了一次次的强降水天气。西南季风加强的时段与几次降水加强时段一一对应。低层锋生作用对梅雨锋有维持和加强作用。梅雨锋区的南侧存在垂直反环流圈。有次级环流上升支触发时,降水增大,造成暴雨增辐。

Analysis of a Continuous Heavy Rainfall Event Occurred During 26-29 June 2013 in Jiangxi

Based on the NCEP 1°×1° reanalysis data and the conventional meteorological data, a continuous rainfall event occurred during 26-29 June 2013 in Jiangxi province is analyzed. The results are as follows： （ 1 ） The heavy rain occurred under the typical Meiyu circulation background, with the breakouts of south Asian high, subtropical high and the southwest monsoon, combining with upper low pressure trough and middle-low level shear simultaneously. （2） There were two water vapor transport channels to provide plentiful vapor for this heavy rainfall. One of them was from Bangladesh Bay transported to northwest side of subtropical high and the other one transmitted along the subtropical high to north. The two kinds of water vapor converged in the northwest subtropical high and strengthened along the edge of subtropical high to south of Yangtze River. The southwest monsoon played an important role on moisture transporting and triggering heavy precipitation, and the heavy precipitation occurred during the southwest monsoon strengthened. Also, the lower layer frontogenesis strengthened the Meiyu front. The vertical inverse circulation was located on the south side of the frontal zone which caused the secondary circulation and triggered the precipitation increase.