山东3次大暴雨过程云街雷达回波特征及其作用分析  

Analysis on Cloudstreet Echo Characteristics and Effects During Three Severe Rainfall Events in Shandong Province

作　　者：刁秀广[1] 刘畅[1] 万明波[1] 侯淑梅[1] DIAO Xiuguang;LIU Chang;WAN Mingbo;HOU Shumei(Shandong Meteorological Observatory,Jinan 250031)

机构地区：[1]山东省气象台

出　　处：《气象》2020年第2期179-188,共10页Meteorological Monthly

基　　金：山东省自然科学基金项目(ZR2016DM20);环渤海区域科技协同创新基金项目(QYXM201802);山东省气象局科研项目(2016sdqxz01)共同资助

摘　　要：利用济南多普勒天气雷达资料,结合探空与天气实况,对山东3次大暴雨过程中云街雷达回波特征和云街对于强降雨的作用进行了分析。结果表明:在天气雷达低层反射率因子上云街表现为多条窄带回波,走向与低层平均风场基本一致,持续时间约6~7 h,强度基本在5~20 dBz。云街对3次强降水的作用主要表现在3方面:一是触发机制,云街可触发对流单体;二是后向传播作用,云街新生对流单体依次沿云街走向向西南方向传播,具有明显后向传播特征,导致对流系统向西偏南方向发展,强降水区也向西偏南方向移动;三是利于降水强度增大和长时间的维持,持续不断的云街激发的雷暴,在移动过程中沿引导气流方向发展并与对流系统主体合并,主体回波得以发展与维持,产生大的雨强,并持续较长时间,导致极端强降雨天气。云街对3次强降水中尺度对流系统的维持与发展及极端强降雨的产生起到了重要作用。2007年7月18日过程云街触发雷暴的频次明显高于其他2次过程,主要原因是对流抑制能量和抬升凝结高度明显小于其他2次过程,更易于雷暴的触发。Based on Jinan Doppler weather radar data,sounding and automatic weather station data,the radar echo characteristics including the effect of cloudstreets on three heavy rainfalls in Shandong Province were analyzed.The results showed as follows.The cloudstreets appear as narrowband echoes oriented in the direction of mean low-level wind in low-level base reflectivity,the duration is about 6-7 hours,and the intensity is about 5-20 dBz.The main effects of cloudstreets on three heavy precipitations are as follows.First is the triggering mechanism.Cloudstreets can trigger convection cells.Second is the backward propagation mechanism.The new storms triggered by cloudstreets spread to the southwest in turn along the orientation of cloudstreets.This backward propagation characteristic can lead the convective system to move toward west by south direction and lead the severe precipitation area to the southwest direction.Third is enhancing precipitation intensity and duration.The continuous storms triggered by cloudstreets develop northeastward under the action of the pilot airflow,and merge with the main echoes of convective system.Therefore,the main echoes will be strengthened,generating large rain intensity and lasting for a long time,finally resulting in extreme severe rainfall weather.The cloudstreets play an important role in the maintenance and development of the three convective systems and in the generation of extreme severe rainfall.The frequency of thunderstorm triggered in the 18 July process is significantly higher than that of the other two processes,and the main reason is that the convective inhibition energy(CIN)is significantly smaller than the other two processes.Small CIN and lifting condensation level are easier to trigger the outbreak of thunderstorms.

关 键 词：云街 触发 后向传播 合并 强降水 

分 类 号：P458[天文地球—大气科学及气象学]