广西2次雷暴大风天气过程的成因及异同分析

Causes and Difference Analysis of Two Thunderstorm Gale Processes in Guangxi

为了加深对华南地区雷暴大风天气形成原因的认识,为此类天气过程预报提供参考,笔者利用常规气象资料、自动站资料、多普勒雷达资料及NCEP再分析资料,分析了2014年3月30—31日广西连续2天大风天气的成因及差异。主要结论:(1)"3.30"过程发生于暖区中;"3.31"过程由地面锋面触发形成。(2)2次过程都具有强的潜在不稳定层结、风暴潜势和中低层垂直风切变,"3.31"过程强度更强。(3)层结廓线均表现为低层湿层明显,湿层之上干层清晰特征,"3.31"过程湿层较浅,比湿较大,干层较深厚。(4)对流风暴均是在地面辐合线附近生成并沿着辐合线移动发展,或者风暴移到辐合线上得到加强。"3.31"过程辐合线尺度大,移动缓慢。(5)雷达回波特征显示,"3.30"过程由局地生成发展的强单体风暴或多单体风暴造成,"3.31"过程由组织性强的飑线(弓形回波)造成,具有相似大风特征。结果显示,有组织性风暴与单体风暴在层结不稳定、中低层垂直风切变的强度及结构、地面辐合线的尺度和移动速度上有明显差异。

This paper aims to further understand the causes of thunderstorm gale in south China and provide a reference for its forecast. Based on conventional observation data, automatic weather station data, Doppler radar data and NECP 1 ~x 1 o reanalysis data, the causes of successive high wind processes in Guangxi and their differences had been studied. Results showed that： （1） the ＂3.30＂ process happened in the warm area, but ＂3.31＂ process was triggered by the surface front; （2） both of the two processes occurred in a favorable environment with an unstable stratification, vertical wind shear and strong storm potential; those conditions were stronger in the ＂3.31＂ process; （3） stratification characteristic showed significantly lower wet layer in both two processes, with clear dry layer on top of it, but the wet layer in ＂3.31＂ process was shallower and with higher specific humidity; （4） convective storms were generated and moved along the surface convergence line or strengthened when moved onto convergence line; the convergence line of ＂3.31＂ process was in a larger scale, which moved slower; （5） radar echo characteristic showed that the ＂3.30＂ process was caused by local single-cell storms or multi-cell storms, but the ＂3.30＂ process was caused by organized large-scale strong squall line （bow echo）. The study indicated that there were differences in the instable stratification, the strength and construction of the mid-low level vertical wind shear and the scale and velocity of the surface convergence line between well organized storm and single-cell storm.