摘要
利用多普勒天气雷达、卫星等观测资料和WRF模式模拟资料,对2016年6月19日发生在赣鄂皖交界地区一次飑线过程的演变特征和环境热力、动力条件进行分析,结果表明:(1)此次飑线过程由多个对流单体组织合并加强形成,降水云团稳定少动。(2)飑线的发生发展与地面辐合线、冷池密切相关,地面辐合线在飑线初期对对流单体有激发、组织作用,飑后气流引导冷空气下沉,配合水汽蒸发吸热形成地面冷池,而冷池向外辐散的气流与西南环境气流在飑线后部形成地面辐合线,新单体在地面辐合线附近发展,使飑线具有"后向"传播特征。(3)垂直于飑线系统方向的低层风垂直切变有利于飑线强对流组织发展,表现为风暴相对入流对水平涡度的转换作用。(4)风暴相对螺旋度是用来衡量风暴入流强弱以及沿入流方向水平涡度分量的大小,随着飑线的不断发展,正螺旋度的数值逐渐增大,飑线成熟时期达到最大,表明低层环境风状况处于最利于强对流系统和气旋性涡旋发展的时期,而后随着飑线系统的消亡逐渐减小。
Using Doppler weather radar,satellite,other observational data and the WRF numerical simulation output,the squall line event that occurred on the boundary of Jiangxi,Hubei and Anhui Provinces on 19 June 2016 is analyzed,focusing on its evolution and the dynamical and thermodynamical characteristics.The results are as follows.(1)The squall was combined and enhanced by several convective cells,and the cloud cluster that causes the heavy rain is almost steady.(2)The development of the squall line is related to the surface converging lines and the cold pool which is formed by cold air mass sinking from higher levels and latent heat cooling during water evaporation.The surface convective lines triggered and organized the convective cells in the formative stage of the squall line.Cold surface outflow associated with the cold pool converged the ambient air flow from the southwest that made the squall line form with a back-propogating feature.(3)The low-level vertical shear,which is vertical to the squall line,enhanced the development of the severe convective cells that served as the conversion between the storm inflow and the horizontal vorticity.(4)The storm relative helicity is used to measure the strength of the inflow to the storm and the horizontal vorticity along the direction of the inflow.The storm relative helicity was increased by the development of the squall line and reached the maximum in the mature stage,which was conducive to the convective system,and then decreased with the dissipation of the squall line.Key words:
作者
肖雯
刘春
陆岳
XIAO Wen;LIU Chun;LU Yue(Jiangxi Public Meteorological Service Center,Nanchang 330029;Jiangxi Meteorological Observatory,Nanchang 330029;Donghai Meteorological Office of Jiangsu Province,Donghai 222300)
出处
《暴雨灾害》
2018年第4期311-318,共8页
Torrential Rain and Disasters
基金
2016年中国气象局预报员专项项目(CMAYBY2016-038)
关键词
飑线
后向传播
低层风垂直切变
风暴相对螺旋度
squall line
back-propogating
low-level vertical shear
storm relative helicity
