贵州一次暖区飑线过程的环境条件和结构特征

Environmental Condition and Structure Feature of a Warm-sector Squall Line Process in Guizhou Province

利用地面常规气象观测资料、自动站加密观测资料、雷达资料和探空资料以及NCEP逐6 h再分析资料,对2018年5月17—18日贵州中北部一次飑线过程的环境条件、形成机制、结构特征进行诊断分析。结果表明:(1)此次过程是一次暖区暖平流强迫类飑线过程,地面无冷空气参与,低空强暖湿平流输送对热力不稳定增长起主导作用,飑线系统具有前导对流线和尾随层状云区的特征,以离散传播为主;(2)由于抬升凝结高度较高,850 hPa切变线的动力抬升是造成此次强对流天气的关键因子,且贵州东部和北部的不稳定条件和能量条件更好,产生的对流更强、密度更大;(3)地面风场扰动辐合线提供触发抬升机制,在触发对流的同时能促进对流组织化发展,对强对流天气预警有较好的指示意义;(4)地面冷池与低层环境风的相互作用对飑线的发展维持起重要作用,飑线朝着前方地面1 h负变压中心和地面中尺度辐合线移动和发展。

Based on conventional observation data,intensive observation data at automatic weather stations in Guizhou,Doppler radar data and the T-ln P profiles and 6-hour reanalysis data from NCEP with 1°×1°spatial resolution,the environmental condition,formation mechanism and structure feature of a squall line in northern and central Guizhou from 17 to 18 May 2018 were analyzed.The results are as follows:(1)There was no cold air on the ground of Guizhou during the influence of the squall line,and the transport of strong warm and wet advection in lower layer played an important role in increasing of thermal instability.The squall line was forced by warm advection,the characteristics of guiding streamline and trailing stratiform cloud area were obvious,and the moving of the squall line was mainly dispersive transmission.(2)The uplift condensation height was higher,so the dynamic uplift of shear line on 850 hPa played a key factor in strong convection weather in central and northern Guizhou.The instability and energy conditions in the east and north were better than that in the central of Guizhou,which was beneficial to stronger convection and higher rainfall density.(3)The convergence line of ground wind disturbance provided triggering and uplift mechanism for the organizational development of convection,which was a good indicator for the early warming of severe convective weather.(4)The interaction of ground cold pool and environment wind in lower layer played an important role in developing and maintaining of the squall line.The squall line moved and developed forward 1-hour allobaric center and ground mesoscale convergence line.