浙江高空冷平流背景下雷暴大风特征分析

Analysis on Characteristics of Thunder-gust Winds Under the Background of Upper-air Cold Advection in Zhejiang Province

从天气形势、环境参数、中小尺度系统以及雷暴结构等方面,本文对浙江省4次高空冷平流背景下不同范围和强度的雷暴大风过程进行研究,得出结论如下:(1)4次强对流过程发生的有利条件主要体现在温度场,△T_(850-500)在30℃以上,γ_(700-400)大于7.1℃·km^(-1);(2)“2006·06·10”和“2009·06·05”过程,△Td_(700-400)平均值大于15℃、CAPE和DCAPE值1100 J·kg^(-1)以上,产生10级以上大风概率较大,另外2次过程深厚湿对流条件较差;(3)近地层湿度条件不同是多单体风暴组织形式不同的主要原因。“2009·06·05”过程出现弓形回波,“2020·04·12”和“2020·04·27”为分散的多单体风暴,但是多单体风暴中嵌有强风暴单体,具有“中层径向辐合”、“阵风锋”等特征,造成了局地雷暴大风。

From the aspects of weather situation, environmental parameters, meso-and small-scale systems and thunderstorm structure, this paper studied four thunder-gust winds processes of different ranges and intensities under the same upper-air cold advection background in Zhejiang Province, and drew the following conclusions:(1) The favorable conditions for the occurrence of severe convection were mainly reflected in the temperature field. △T_(850-500)was more than 30 ℃, and γ_(700-400)was more than 7.1 ℃·km^(-1);(2)In “2006.06.10” and “2009.06.05” processes, the average value of △Td_(700-400)was ≥15 ℃, the CAPE and DCAP were both ≥1100 J·kg^(-1),then the probability of generating thunder-gust wind above 10 level was high, but the other two processes were poor;(3) The intensity and organizational development of storms were also different due to the different humidity conditions of the surface layer.In the “2009.06.05” process formed the bow echo;“2020.04.12” and “2020.04.27” had scattered multi-cell storms, but there were strong storm cells in the multi-cell storms, which had the characteristics of “mid-level radial convergence” and “gust front”, resulting in local thunder-gust winds.