2018年8月13—15日大连地区大暴雨过程环流形势诊断分析

Diagnosis and Analysis on Circulation Situation of Rainstorm Process in Dalian Area from August 13th to 15th, 2018

本文利用NCEP再分析资料、自动站实况资料等对2018年8月13—15日大连地区的一次暴雨过程进行了分析。结果表明:此次暴雨过程主要受副高外围云系台风“摩羯”残余环流以及北部冷空气的共同影响。其中,降水前期13日至14日白天主要受副高外围云系和北部冷空气的共同影响。14日夜间至15日白天台风“摩羯”残余环流入渤海后加强,此次环流入海发展过程中始终位于500 h Pa高空槽前和副高外围云系后部,槽前正涡度平流、槽后冷空气的汇入以及强烈暖平流是气旋爆发性发展的主要原因。高空辐散、低空辐合以及强上升运动为环流发展提供了动力条件,雷达回波强度上主要降水时段出现了类似列车效应的强降水回波带,而VIL值维持在20 kg/m^(2)以上,数值模式中欧洲中心对于第一阶段的降水预报较理想,而对于环流入海加强这一现象所有模式均未能准确及时预报。

In this paper,NCEP reanalysis data and automatic station data were used to analyze a rainstorm process in Dalian area from August 13th to 15th,2018.The results showed that the rainstorm process was mainly influenced by the residual circulation of typhoon Yagi in the periphery cloud system of the subtropical high and cold air in the north.During the early precipitation period from August 13th to the day of 14th,it was mainly influenced by the periphery cloud system of the subtropical high and the cold air in the north.From the night of August 14th to the day of 15th,the remnant ring of typhoon Yagi entered the Bohai Sea and strengthened.During the development process of the circulation,the remnant ring was always located in front of the upper trough and behind the periphery cloud system of subtropical high at500 h Pa.The positive vorticity advection in front of the trough,the inflow of cold air behind the trough and the strong warm advection were the main reasons for the explosive development of the cyclone.Divergence at high altitude,convergence at low altitude and strong ascending motion provided dynamic conditions for the development of circulation.In terms of radar echo intensity,a strong precipitation echo belt similar to train effect appeared in the main precipitation period,while the VIL value remained above 20 kg/m^(2).In the numerical model,the European Center had an ideal precipitation forecast for the first stage.For the phenomenon of circulation intensification into the sea,all models did not accurately and timely report.