FY-4A卫星和X波段雷达在一次混合强对流过程中的应用分析

Application Analysis of FY-4A Satellite and X-Band Radar in a Mixed Severe Convection Process

摘要: 为探究高原地区混合强对流天气的监测与预警技术，利用FY-4A卫星多通道观测数据、乐都新一代X波段双偏振雷达资料及地面观测实况，对2023年6月12日发生在青海海东市的混合强对流过程(含冰雹、雷暴大风及罕见EF1级龙卷)进行系统分析。结果表明：此次强对流由高空短波槽、低层热低压及低空切变线共同触发，“上冷下暖”的不稳定层结与充足的对流有效位能为其提供了有利条件；FY-4A卫星可见光通道的上冲云顶、水汽通道的楔形湿区推进及红外通道≤220 K的云顶亮温可有效指示强对流发展；乐都X波段双偏振雷达30米高距离分辨率与1˚仰角分辨率的配置，成功捕捉到冰雹的“穹窿”回波结构及龙卷的龙卷涡旋特征(TVS)与龙卷碎片特征(TDS)；冰雹落区对应Z_DR ≤ 0 dB、CC ≤ 0.94、K_DP ≤ 1˚/km的偏振参数组合，龙卷过程则表现为CC异常低值(0.75~0.83)与Z_DR剧烈波动的协同特征。卫星与雷达的协同观测构建了“宏观云系–微观粒子”的全维度监测体系，为高原地区强对流天气的短临预警提供了重要技术支撑。

Abstract: To explore the monitoring and early warning technologies for mixed severe convective weather in plateau areas, this study systematically analyzes the mixed severe convective process (including hail, thunderstorm gales, and a rare EF1 tornado) that occurred in Haidong City, Qinghai Province on June 12, 2023, using multi-channel observation data from FY-4A satellite, data from the new-generation Ledu X-band dual-polarization radar, and ground observation facts. The results show that this severe convection was jointly triggered by upper-air short-wave trough, low-level thermal low, and low-level shear line, with the “upper cold and lower warm” unstable stratification and sufficient convective available potential energy (CAPE) providing favorable conditions. The overshooting top in the visible channel, the advancement of wedge-shaped moist area in the water vapor channel, and the cloud top brightness temperature (TBB) ≤ 220 K in the infrared channel of FY-4A satellite can effectively indicate the development of severe convection. The configuration of 30-meter high range resolution and 1˚ elevation angle resolution of the Ledu X-band dual-polarization radar successfully captured the “vault” echo structure of hail, as well as the tornado vortex signature (TVS) and tornado debris signature (TDS) of the tornado. The hail fall area corresponds to the polarization parameter combination of Z_DR ≤ 0 dB, CC ≤ 0.94, and K_DP ≤ 1˚/km, while the tornado process is characterized by the synergy of abnormally low CC values (0.75~0.83) and drastic Z_DR fluctuations. The synergistic observation of satellite and radar has constructed a full-dimensional monitoring system of “macro cloud system-micro particles”, providing important technical support for the short-term and imminent early warning of severe convective weather in plateau areas.