四川盆地西北侧一次飑线与MCS相互作用的诊断分析  

Diagnostic Study of a Squall Line and MCS Interaction on the Northwest Side of Sichuan Basin

作　　者：周昱 李国平[1] ZHOU Yu;LI Guoping(College of Atmospheric Sciences,Chengdu University of Information Technology,Chengdu 610225,China)

机构地区：[1]成都信息工程大学大气科学学院,四川成都610225

出　　处：《成都信息工程大学学报》2024年第5期571-580,共10页Journal of Chengdu University of Information Technology

基　　金：国家自然科学基金资助项目(42175002、42075013);四川省自然科学基金资助项目(2023NSFSC0242)。

摘　　要：为更好理解飑线与MCS这两种典型中尺度系统相互作用过程中热力、动力、水汽与微物理的基本特征及其演变规律,利用ERA5再分析资料、GPM及FY-4A卫星资料,对2018年7月1-2日发生于四川盆地西北侧一次飑线与MCS相互作用过程进行诊断分析。得出的主要结果有:(1)受高原槽、低层切变线及复杂地形的共同作用,飑线东南移动过程中,先爬坡加强,后下坡减弱,与原地少动的中尺度对流系统(mesoscale convective system,MCS)合并后,二者有明显的热力、动力、水汽等物理量交换,飑线减弱而MCS加强。(2)在两种中尺度天气系统发生相互作用前,对流有效位能大值区由“零散点状分布”转变为“集中式大范围分布”。(3)“上正下负”的位涡垂直配置与中层较小的正热力螺旋度均能较好指示系统的加强,中低层水汽通量辐合与中层较小的正水汽螺旋度相呼应。(4)飑线与MCS合并前,飑线以冷云降水过程为主,MCS则以暖云降水过程为主;二者开始合并至合并完成后,受飑线的影响,MCS的0℃层以上雪水与冰水含量有明显提升,MCS降水转为暖云与冷云降水共同作用。该研究可为加深认识两类中尺度系统相互作用过程提供理论参考,对其预警预报也有一定指导意义。To better understand the basic characteristics and evolution patterns of thermodynamics,dynamics,water vapor,and microphysics in the interaction process between the two typical mesoscale synoptic systems,this article used ERA5(the fifth generation hourly reanalysis data from the European Centre for Medium-Range Weather Forecasts)reanalysis data,GPM(Global Precipitation Measurement)and Chinese FY-4A satellite data to diagnose and analyze the interaction process between the squall line and MCS(MesoscaleConvective System)that occurred from July 1 to 2,2018 on the northwest side of the Sichuan Basin.The main results obtained wereas follows:(1)Under the joint influence of the plateau trough,low-level shear line,and complex terrain,the squall line moved southeast,strengthening first when climbing,and then weakening when descending.After merging with the MCS with minimal movement in place,there was a significant exchange of matter and energy between the two,and the squall line weakened and MCS strengthened.(2)Before the interaction between the two mesoscale synoptic systems,the high-value area of convective available potential energy(CAPE)changed from a"scattered spot distribution"to a"concentrated large area distribution".(3)The configuration of the"upper positive and lower negative"potential vorticity,as well as the smaller positive thermal helicity in the middle layer,could effectively indicate the strengthening of the system.The convergence of the water vapor flux in the middle and lower layers corresponded to the smaller positive water vapor helicity in the middle layer.(4)Before the merger of the squall line and MCS,the squall line were dominated by the cold cloud precipitation process,while the MCS was dominated by the warm cloud precipitation process;During the period from the beginning of the merger to the completion of the merger,due to the influence of the squall line,the specific snow water content and specific cloud ice water content above 0℃of the MCS significantly increased,and the precipitation of the

关 键 词：飑线 MCS 四川盆地 相互作用 诊断分析 

分 类 号：P434.5[天文地球—大气科学及气象学]