登陆台风中的中尺度对流系统的数值研究

Numerical Study of the Mesoscale Convective Systems in Landfall Typhoon Herb

应用PennState NCAR高分辨率中尺度模式MM5 ,成功模拟出 1996 0 8 0 3到 0 5Herb(1996 )台风登陆后 ,发生在河北及周边地区台风低压暴雨中的两个连续发展的中α尺度对流系统的演变和结构 ,它们与降水量实况有很好地对应。由此根据模式输出结果分析了这两个中尺度对流系统(MCS)的中尺度结构和特点 ,最后给出了登陆台风低压暴雨的MCS结构模型 ;在MCS成熟期 ,低层大尺度的低空急流 (LLJ)中出现中尺度扰动 ,即中尺度低空急流 (mLLJ) ,mLLJ的左前方产生强辐合和上升运动 ,在上升气流的高空出流区域产生中尺度高空急流 (mULJ) ,这种mULJ在常规观测资料中被验证。mULJ的右后方有强辐散发生。

The evolution and structure of two organized meso-α-scale convective systems developed sequentially on the landfall typhoon low during 3-5 August 1996 are simulated successfully using Penn State/NCAR mesoscale model version 5(MM5).The simulated cloud and precipitation are coincident with the satellite and conventional precipitation observations,respectively.Based on the model output,the detail structure and characteristic of MCS are studied,and the air trajectories around these MCSs are also calculated.Finally,a concept model of MCS in landfall typhoon was given out;In mature stage,the mesoscale Low-Level Jets(mLLJs) act as mesoscale disturbances that embedded in the synoptic-scale Low-Level Jets(LLJs)at the low-level.Strong convergence and upward motion occurred on the left-front of the mLLJ.Mesoscale Upper-Level Jets(mULJs) was found in the upper level outflow caused by upward motion.This mULJ can be verified from conventional upper-air soundings.Strong divergence happened in the right-rear of the mULJ in simulation.