贵州地区地面辐合线触发强对流天气机理研究初探

Preliminary Study on the Mechanism of Strong Convection Triggered by Surface Convergence Lines in Guizhou Region

摘要: 利用贵州省常规观测和区域加密自动观测站资料、葵花8及天气雷达观测资料，通过水汽、能量、抬升三个方面研究贵州区域地面辐合线对强对流天气的触发机制。首先对造成贵州区域强对流天气的地面辐合线进行分型：按照动态分为移动型、静止型、碰撞型三种，按照形态分为成东北–西南型、准横向型、西北–东南型、南北型，其中东北–西南型和南北型多移动，准横向型和西北–东南型多静止。然后通过分析地面辐合线与强对流天气落区的位置关系，发现绝大多数强对流天气落区位于辐合线后部及上部，且距离辐合线水平距离均在20 km以内。最后通过分析强对流天气发生前地面辐合线附近温、湿度情况，发现三种地面辐合线两侧的温差大部分为2℃~4℃，露点差为1.5℃~3.5℃，并发现三种不同辐合线触发强对流天气时的对流有效位能(CAPE)均需达到1000 J/kg以上，强天气威胁指数(SWEAT)需达到230以上，且抬升凝结高度和自由对流高度均需低于700 hPa高度。

Abstract: Using conventional observation data from Guizhou Province, regional encrypted automatic ob-servation stations, sunflower 8, and weather radar observation data, this study investigates the triggering mechanism of surface convergence lines on strong convective weather from three as-pects: water vapor, energy, and uplift. Firstly, the surface convergence lines that cause severe convective weather in the Guizhou region are classified into three types: moving, stationary, and collision based on their dynamics. They are divided into northeast southwest type, quasi trans-verse type, northwest southeast type, and north-south type based on their morphology. Among them, the northeast southwest type and north-south type are mostly moving, while the quasi transverse type and northwest southeast type are mostly stationary. Then, by analyzing the positional relationship between the surface convergence line and the strong convective weather zone, it was found that the vast majority of the strong convective weather zone is located behind and above the convergence line, and the horizontal distance from the convergence line is within 20 kilometers. Finally, by analyzing the temperature and humidity conditions near the surface convergence line before the occurrence of strong convective weather, it was found that the temperature difference on both sides of the three types of surface convergence lines was mostly 2˚C~4˚C, and the dew point difference was 1.5˚C~3.5˚C. It was also found that the convective effective potential energy (CAPE) of the three different convergence lines needed to trigger strong convective weather needed to reach above 1000 J/kg, and the strong weather threat index (SWEAT) needed to reach above 230, and the elevation of condensation height and free convection height should be lower than the height of 700 hPa.