多源新型探测资料在一次局地短时暴雨中的应用

Application of multi-source new-type detection data in a local short time rainstorm

摘要:

基于S波段双偏振天气雷达、毫米波云雷达、微波辐射计和激光气溶胶雷达等多源新型探测资料，对2023年8月6日浙江金华一次局地短时暴雨的环境场和降水云结构特征展开分析。结果表明：（1）上干冷、下暖湿的温湿层结提供不稳定条件，地面中尺度冷锋和气旋性涡旋提供有利的动力和热力触发机制。（2）差分反射率因子ZDR和差分相移率KDP迅速增大并形成伸展高度接近0 ℃层的ZDR柱和KDP柱，表明存在强的上升气流和降水强度，可以为短时暴雨预警提供重要参考。（3）毫米波云雷达能提前20 min观测到对流云发展，回波顶高迅速伸展至12 km、反射率因子迅速增强至30 dBZ以上、高层径向速度迅速增加至10 m·s-1对短时暴雨有一定指示意义。（4）微波辐射计的综合水汽含量、积分液态水含量分别跃增至90 kg·m-2、10 g·m-2且维持较长时间可作为短时暴雨预警的参考指标。（5）激光气溶胶雷达消光系数大于2、退偏振比大于0.3的“高消光、高退偏”图谱特征能较好地指示短时暴雨。

Abstract:

Based on multi-source new-type detection data from S-band dual-polarization weather radar, millimeter wave cloud radar, microwave radiometer and laser aerosol radar, environmental background and structure characteristics of the precipitation cloud in a local short time rainstorm occurred in Zhejiang Jinhua on 6 August 2023 were diagnosed. The results show that: (1) Temperature and humidity stratification of cold and dry air above but warm and wet air below provides the unstable condition; Surface medium scale cold front and cyclonic vortex provide favorable dynamic and thermodynamic trigger mechanisms. (2) Both differential reflectivity (ZDR) and specific differential phase (KDP) increase rapidly, leading to the formation of ZDR and KDP columns with extended height close to 0 ℃ layer, which indicate the existence of strong updraft and precipitation intensity and can provide an important reference for short time rainstorm warning. (3) Millimeter wave cloud radar can detect development of the convective cloud 20 min in advance; Rapid extension of echo top height to 12 km, rapid increase of reflectivity factor to more than 30 dBZ, and rapid increase of radial velocity to 10 m·s-1 in the upper layer have certain indicative significance for short time rainstorm. (4) Integrated Water Vapor and Integrated Liquid Water Content of microwave radiometer jump to 90 kg·m-2 and 10 g·m-2 respectively and maintain for a long time, which can be used as a reference index for short time rainstorm warning. (5) Laser aerosol radar with “high extinction and high depolarization” spectra of extinction coefficient greater than 2 and depolarization ratio greater than 0.3 can indicate short time rainstorm well.