桂北一次强降水过程的诊断分析

目的]分析2010年5月27-28日桂北一次强降水过程。方法]利用2.5°×2.5°的NCEP再分析资料,对2010年5月27-28日广西桂北一次锋面暴雨过程的水汽通量、假相当位温、非地转湿Q矢量等物理量进行诊断分析,重点探讨非地转湿Q矢量在广西前汛期锋面暴雨落区中的预报应用。结果]孟加拉湾水汽向广西输送,并在桂北产生强的辐合上升运动,为桂北强降水的发生提供了有利的水汽输送条件。850 hPa假相当位温锋区（密集区）南压至广西北部,桂北处在假相当位温锋区中,低层高湿的不稳定能量与中层向下渗透的冷空气导致中低层位势不稳定建立,从而为此次强降水过程提供了一定的热力条件;广西北部低层850 hPa处在等Qx＊值线梯度最大区域和较强的Q矢量散度负值区重叠的区域,为未来桂北的暴雨过程提供了有利的动力条件。结论]该研究为暴雨预报提供参考依据。

Diagnosis of a Heavy Precipitation Process in Northern Guangxi

Objective] The aim was to analyze one strong precipitation process in Northern Guangxi from May 27 to 28 in 2010.Method] By dint of 2.5°×2.5° NCEP reanalysis data,physical quantities such as the water vapor flux,pseudo-equivalent temperature,ageostrophic wet Q vector in one front rainstorm process in north Guangxi Province from May 27 to 28 in 2010 was expounded.The forecast application of ageostrophic wet Q in rainstorm falling area in Guangxi during early flood period was discussed.Result] The water vapor in Bay of Bengal transported to Guangxi and formed convergence lifting movement in north Guangxi,which provided favorable water vapor transportation condition for the generation of strong precipitation in north Guangxi.The 850 hPa pseudo-equivalent temperature front(close area) moved southward to the north part of Guangxi Province.North Guangxi was in pseudo-equivalent temperature area.The highly wet unstable energy of lower layer and the cold air penetrating downward from the middle layer led to potential instability in the lower level established in northern Guangxi,which thus provided certain thermal condition for the strong precipitation process;Northern Guangxi was in the overlap region of the maximum gradient region of contour Q*x at 850 hPa and stronger negative areas of Q,which provided favorable dynamic condition for the rainstorm process in northern Guangxi in the future.Conclusion] The study provided reference accordance to the forecast of rainstorm.