低涡切变暴雨环流特征及物理量特征分析

Analysis of circulation characteristics and physical quantity characteristics of low vortex shear storm

根据铜仁10个站点2013-2017年雨量资料,选取5-7月的区域暴雨个例,利用常规天气资料和NECP资料,总结了暴雨天气的主要影响系统,对比分析了冷性低涡切变暴雨和暖性低涡切变暴雨的环流特征及物理量特征。分析发现,①冷性低涡切变暴雨的环流特征表现为:500hPa高空副高脊线稳定,多波动槽,中低层有明显的低涡切变,低涡中心在川渝一带,东移路径;地面无明显锋面,有弱冷空气渗透,多以偏北路径为主,无明显降温;其发生频率是低涡切变型暴雨的33%,以5-6月为主。②暖性低涡切变暴雨的环流特征表现为:500hPa高空副高脊线稳定,中低层有明显的低涡切变,850hPa低涡多位于铜仁上空,东移南下路径;地面多为均压场,处于暖低压底部,海上高压后部;其发生频率是低涡切变型暴雨的67%,以6-7月为主。③冷性和暖性低涡切变暴雨物理特征表现为:水汽条件在暴雨发生时段最大,结束时减小;动力条件和热力条件及k指数在暴雨发生前、发生时两个时段逐渐增大(发生时最大),发生后减小;其他不稳定能量条件没有规律;暴雨的发生与不稳定能量的相关性不大。

According to the rainfall data of 10 sites in Tongren from 2013 to 2017,regional rainstorm cases from May to July were selected. Using regular weather data and NECP data,summarizing the main impact systems of heavy rains,the circulation characteristics and physical quantity characteristics of cold low vortex shear storm and warm low vortex shear storm were compared and analyzed. Analysis found that:①The circulation characteristics of cold low vortex shear storm are:The 500 hPa high altitude subtropical high ridge line is stable. Multi-fluctuation groove,There are obvious low vortex shears in the middle and lower layers. The low vortex center is in the area of Sichuan and Chongqing. Eastward path;There is no obvious front on the ground. There is weak cold air penetration,Mostly based on the northerly path,No significant cooling;Its frequency is 33% of low vortex shear storms. It is mainly from May to June.②The circulation characteristics of warm low vortex shear storms are as follows: The 500 hPa high altitude subtropical high ridge line is stable. There are obvious low vortex shears in the middle and lower layers. The 850 hPa low vortex is mostly located above the Tongren. Move eastward to the south;The ground is mostly a pressure equalization field. At the bottom of the warm and low pressure,The rear part of the sea;Its frequency is 67% of low vortex shear storms. It is mainly from June to July.③The physical characteristics of cold and warm low vortex shear storms are as follows: The water vapor condition is the largest during the rainstorm period. Decrease at the end;Dynamic conditions and thermal conditions and k-index gradually increase in two periods before and during the occurrence of heavy rain (maximum occurrence),Decrease after occurrence;Other unstable energy conditions are irregular;The occurrence of heavy rain is not related to unstable energy.