Abstract:

In order to systematically study the characteristics of thunderstorm gust fronts in Hubei, Doppler radar data and automatic weather station data from 2016 to 2021 in Hubei Province are used to make a comprehensive statistical analysis. The results are as follows: (1) Gust fronts mainly occurred from June to August in Hubei Province, accounting for 96% of the total, and in August it was the most. The gust front mainly occurred during 15:00-18:00 in a day with the peak value at 17:00, and most gust fronts lasted for 1.5-3.0 h. Among the mother thunderstorms that generated gust fronts, 35% were multi-cell thunderstorms, 40% were multi-cell thunderstorm groups, and 25% were squall lines. (2) There were five main generation areas of gust fronts, including the area outside the province, the northeast Hubei, the Jianghan Plain, Xiangyang in the northwest Hubei and Yichang in the southwest Hubei, and the moving direction of gust fronts generated in the same area had good regularity. The gust fronts in the northeast Hubei was the most, accounting for 33% of the total. (3) Not all mother thunderstorms and their gust fronts can cause surface gales. The maximum ground wind speed generated by 69% mother thunderstorms and 9% gust front was equal to or greater than 17.0 m·s^-1. In multi-cell thunderstorm and multi-cell thunderstorm groups, the stronger the echo intensity of the mother thunderstorm, the greater the probability of surface gale generated by the mother thunderstorm and its gust front, and the intensity of surface wind speed generated by the gust front had little relationship with the echo intensity and spatial scale. (4) Gust fronts had strong convective triggering ability, and 91% of gust fronts can trigger convective cells behind, near and in front of them. The feedback effect of the thunderstorm and its gust front is different, and the relative position of the convection trigger and the gust front is different. The positive feedback type mostly triggered convection behind the gust front. The negative feedback type can trigger convection behind, near and in front of the gust front, the intensity of 29% of convective cells was equal to or greater than 55 dBZ. The 35% of the gust fronts merged with the surrounding thunderstorms to form a combined gust front, which occurred most in the northeast Hubei.

Key words: Hubei, gust front, squall line, multi-cell storms, convective triggering

摘要：

基于2016—2021年湖北多普勒雷达及加密自动气象站资料，对湖北雷暴阵风锋特征进行分析。结果表明：（1）湖北阵风锋主要出现在6—8月，占总数的96%，其中8月最多；一天中主要发生时段为15：00—18：00（北京时，下同），峰值在17：00；大多数阵风锋持续时间为1.5~3.0 h；产生阵风锋的母雷暴中35%为多单体雷暴，40%为多单体雷暴群，25%为飑线。（2）阵风锋主要有5个生成区域，分别为省外、鄂东北、江汉平原、鄂西北的襄阳和鄂西南的宜昌，相同区域生成的阵风锋移动方向有较好的规律性。鄂东北生成的阵风锋最多，占总数的33%。（3）不是所有母雷暴及其阵风锋都能引发地面大风，69%的母雷暴和9%的阵风锋产生的地面极大风速大于等于17.0 m·s^-1。在多单体和多单体雷暴群中，母雷暴的回波强度越强，母雷暴及其阵风锋产生的地面大风概率越大，阵风锋产生的地面风速强度与其回波强度、空间尺度关系不大。（4）阵风锋有较强对流触发能力，91%的阵风锋在其后部、附近和前侧触发对流单体。母雷暴与其阵风锋反馈作用不同，对流触发与阵风锋的相对位置有差别，正反馈型大多在阵风锋后部触发对流，负反馈型在阵风锋后部、附近和前侧均可触发对流，29%的触发对流回波强度大于等于55 dBZ。35%的阵风锋与周边已有雷暴合并发展形成合并型阵风锋，此型在鄂东北发生次数最多。

关键词: 湖北, 阵风锋, 飑线, 多单体, 对流触发