信江流域大暴雨中的短时强降水回波特征分析

Analysis of Echo Characteristics of Short-term Heavy Rainfall in Heavy Rainstorm in Xinjiang River Basin

  • 摘要: 本文利用MICAPS常规天气资料、自动站气象资料和雷达回波等资料,对江西信江流域大暴雨过程中发生短时强降水(≥30 mm/h)的雷达回波特征进行分析。结果表明:(1) 信江流域短时强降水有5种回波形态,分别是回波短带、絮状回波团、飑线回波带、回波带上超级单体和孤立单体。(2) 飑线回波带和回波带上超级单体均表现出典型的强对流回波特征,回波强度可达65 dBZ,垂直积分液态含水量(Vertically Integrated Liquid Water,VIL)在55~60 kg/m2,有时伴有冰雹、雷暴大风等强对流天气;回波短带、絮状回波团和孤立单体的回波强度在45~55 dBZ,VIL在5~20 kg/m2,均属于低质心降水回波。(3)当回波强度≥45 dBZ且强回波面积为200~399 km2时,易产生≥5 mm/10 min雨强;当回波强度≥50 dBZ且强回波面积≥500 km2时,易产生≥10 mm/10 min雨强。(4)信江流域短时强降水发生时,3 km高度存在风向和风速的显著辐合,促使对流单体形成和发展。

     

    Abstract: Based on MICAPS routine weather data, automatic weather station meteorological data and radar echo data, the radar echo characteristics of short-term heavy precipitation (≥ 30 mm/h) during heavy rainstorm in Xinjiang River Basin of Jiangxi Province are analyzed. The results indicate that: (1) There are five echo forms of short-term heavy precipitation in the Xinjiang River Basin, which are short echo band, flocculent echo cluster, squall line echo band, supercell on echo band, and isolated cell. (2) The squall line echo band and the supercell on the echo band exhibit typical strong convective echo characteristics, with echo intensity reaching 65 dBZ and Vertical Integrated Liquid Water (VIL) ranging from 55 to 60 kg/m2, sometimes accompanied by strong weather such as hail, thunderstorms, and strong winds. The echo intensity of the other three echo forms ranges from 45 to 55 dBZ, and the VIL ranges from 5 to 20 kg/m2, belonging to low centroid precipitation echoes. (3) When the strong precipitation echo intensity is ≥45 dBZ, strong echo area is 200~399 km2, producing ≥5 mm/10 min rain intensity. When the echo intensity is ≥50 dBZ and the strong echo area is ≥500 km2, it is easy to generate ≥10 mm/10 min rain intensity. (4) When short-term heavy rainfall occurs in the Xinjiang River Basin, there is a significant convergence of wind direction and speed at a height of 3 km, which promotes the formation and development of convective cells.

     

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