贵州一次连续暴雨的低值系统及湿位涡分析

利用自动站资料以及NCEP再分析资料,对2017年6月末贵州区域连续暴雨过程进行分析。结果表明:连续暴雨期间,西太平洋副热带高压位置较常年偏强,副高西伸脊点偏西,副高西北侧的西南风为持续性暴雨提供水汽输送;东亚中纬度地区维持“西高东低”形势,有利于引导冷空气南下影响贵州,与西南暖湿气流在贵州交汇,这种大尺度系统的稳定维持有利于连续暴雨的发生;贵州西部地区的低值系统是造成贵州区域连续暴雨的重要中尺度系统;MPV1低层负值区,高层正值区的配置为贵州暴雨的有利形势;低层辐合高层辐散的形势使得贵州区域呈现强烈的上升运动,为连续性暴雨提供有利的动力条件,同时低层水汽丰富并伴有强的水汽辐合,为连续性暴雨提供有利的水汽条件。

ANALYSIS OF LOW-PRESSURE SYSTEM AND MOIST POTENTIAL VORTICITY OF A CONTINUOUS RAINSTORM IN GUIZHOU

Based on the automatic station data and NCEP reanalysis data,the continuous rainstorm process in Guizhou at the end of June 2017 was analyzed.The results show that:during the continuous rainstorm,the location of the Western Pacific Subtropical High is stronger than usual year,and the western ridge point of the Western Pacific Subtropical High is westward;the southwestern wind on the northwest side of the Western Pacific Subtropical High provides water vapor for continuous rainstorm;Maintenance of the“high west-low east”situation in the mid-latitudes is conducive to guiding the cold air advance south and influence Guizhou,and then meet with the warm-wet air from southwestern in Guizhou,the stability of this large-scale system is conducive to form a continuous rainstorm.The Low-pressure System in western Guizhou is an important mesoscale system that causes continuous rainstorm in the Guizhou.The situation of the MPV1 negative area at low layer and positive area at high layer are the favorable forms of rainstorm in Guizhou.The situation of lower convergence and upper divergence has given rise to a strong upward movement in the Guizhou,providing a powerful dynamic condition for continuous rainstorm.At the same time,the rich water vapor at low layer accompany strong water vapor convergence,which provides favorable vapour conditions for continuous torrential rain.