一次强降水超级单体风暴的动力特征分析  

Analysis on the Dynamic Characteristic of a Heavy Precipitation Supercell Storm

作　　者：李曦 LI Xi(Guangan Weather Bureau,Guangan 638500,China)

机构地区：[1]四川省广安市气象局,四川广安638500

出　　处：《中低纬山地气象》2020年第5期32-40,共9页Mid-low Latitude Mountain Meteorology

摘　　要：利用NCEP/NCAR(0.25°×0.25°)逐6 h再分析资料、常规观测资料、多普勒雷达资料对2018年9月19日晚发生在四川盆地东北部的强降水超级单体风暴进行诊断分析。研究表明:此次强降水超级单体风暴发生在较强的不稳定能量、很低的抬升凝结高度、低层深厚湿层、较弱的对流抑制能量及中等到强的垂直风切变的背景条件下,低层冷空气的侵入最终触发了本次过程。在强降水超级单体风暴发展演变过程中,中低层较强垂直风切变的重要作用是产生水平涡管。水平涡管又在上升气流的作用下抬升为垂直涡管,最后产生垂直涡度。而通过对大气垂直涡度方程的分析发现:垂直涡管在随高度增加的上升气流的拉伸作用下,不断加强,致使上升气流更强烈旋转,水平旋转又反过来加强了上升气流。上升气流与水平涡旋持续不断的正反馈机制是形成中气旋的重要原因。Based on the data from the 0.25°×0.25°NCEP/NCAR reanalysis data of 6 hours and conventional weather observations,Doppler radar data,a heavy precipitation supercell storm which hit the Northeast Sichuan Basin at night on 19 September 2018 is diagnostically analyzed.The research shows:This heavy precipitation supercell storm occurred under the background conditions of strong unstable energy,very low uplifting condensation height,deep wet layer at low level,weak convective suppression energy and moderate to strong vertical wind shear,and the invasion of cold air at low level finally triggered this process.The stronger vertical wind shear at low-middle layer produced horizontal vortex tube in the developing process of the heavy precipitation supercell.The horizontal vortex tube became a vertical vortex tube during stretching process of updrafts and the horizontal vortex tube generated the vertical vorticity.As the vertical vortex tube strengthens continuously during stretching process of updrafts,the updrafts produced a stronger rotation which enhanced the updrafts.The important reason to the formation of mesocyclones was the positive feedback mechanism between the updrafts and horizontal rotation.

关 键 词：强降水超级单体 正反馈机制 垂直风切变 涡度方程 

分 类 号：P426.6[天文地球—大气科学及气象学]