一次多灾种强对流天气成因及双偏振雷达特征分析

Analysis on causes of a multi-disaster convective weather and associated characteristics of dual-polarization radar echoes

摘要:

摘要：2022年6月12日下午至夜间，北京东部出现一次包含极端短时强降水、雷暴大风、大冰雹的多灾种强对流天气，利用地面加密自动站、欧洲中心ERA5、GPS/MET水汽、北京双偏振雷达等多源观测数据，着重探讨和分析本次强对流天气成因和双偏振雷达特征。结果表明：（1）本次强对流天气发生在东北冷涡与低层偏南气流和暖脊叠置区域，强垂直风切变和近地面东南风携带的大量水汽，增加了该区域的对流潜势。（2）对流发生后冷空气在山前堆积，前沿不断触发新生对流，导致强对流天气长时间维持。（3）双偏振雷达低仰角ZDR接近0 dB、CC降至0.85～0.95，表现出明显的冰雹云特征，ZDR柱伸展到-20 ℃层以上，对应CC小值区和KDP洞，表明该位置上升气流强盛，有利于冰雹增长；大风出现在低仰角速度大值区，反射率因子和KDP梯度大值区前沿，单体质心高度的迅速下降，加剧了地面大风；强降水时段随着Z的增大，ZDR和KDP均呈增大趋势，雨强随低层KDP的跃增而迅速增大。

Abstract:

Abstract:From the afternoon to night on June 12,2022, multi-disaster convective weather including extreme heavy precipitation，thunderstorm wind and hail occurred in eastern Beijing．Using the ground automatic encryption observation station data、ERA5 reanalysis data、GPS/MET water vapor data and the dual-polarization radar data in Beijing, causes of a severe convective weather and the dual-polarization radar characteristics are analyzed. The results show that：(1) This severe convective weather occurs in the area where the Northeast China Cold Vortex superimposes on the low-level warm ridge. The near surface water vapor transport and strong vertical wind shear further enhance the convective potential. (2) Cold air accumulates in front of the mountain after convection occurs.The front of the cold air zone continuously triggers new convection, leading to the long-term maintenance of strong convective weather. (3) The low elevation ZDR of the dual polarization radar is close to 0 dB, and the CC drops to 0.85~0.95, showing obvious hail cloud characteristics. The ZDR column extends to -20 ℃ isothermal line. The low level of CC and the hole of KDP appear in this area. The strong upward airflow at this location is conducive to the growth of hail. Strong wind appears at the forefront of low elevation velocity high value areas and reflectivity factor and KDP gradient high value areas. The rapid decline in the height of the center of mass has intensified strong winds on the ground. During the period of heavy rainfall, both ZDR and KDP show an increasing trend with the increase of Z. The rainfall intensity rapidly increases with the leap of low-level KDP.