一次暴雨过程中非线性亚临界对称不稳定的机制分析  

Analysis of Nonlinear Subcritical Symmetric Instability Mechanism in a Rainstorm Process

作　　者：李燚[1] 陆维松[2] 濮梅娟[3] 邵海燕[2] 陶丽[2] 

机构地区：[1]南京信息工程大学江苏省气象灾害重点实验室,江苏南京210044 [2]南京信息工程大学大气科学学院,江苏南京210044 [3]江苏省气象局气象台,江苏南京210008

出　　处：《南京气象学院学报》2008年第3期340-351,共12页Journal of Nanjing Institute of Meteorology

基　　金：国家教育部高等学校博士学科点专项科研基金资助项目(20040300002);国家自然科学基金资助项目(40275016)

摘　　要：对2005年7月5日20时—12日08时淮河流域、安徽中北部的降水过程诊断分析,并利用WRF模式对7月6日08时—7日20时安徽中部的暴雨过程进行数值模拟,结果表明:(1)2005年7月5日20时—12日08时降水过程可分为2大段,非线性亚临界对称不稳定可能是该时段强降水形成的重要机制;(2)u和v两分量扰动增强均超前于暴雨的增强,并对强暴雨的发生有指示作用;非地转作用达最强和冷暖空气达最强分别对强暴雨发生也有12或24 h的指示作用;(3)得到降水强度、高低空急流及其扰动风场这5者极大值的时空配置;(4)得到暴雨前期,高低层涡度场和散度场的时空配置特征。由以上4点及垂直上升气流的变化提出非线性亚临界对称不稳定激发强暴雨形成的新的物理机制。Diagnostic analyses are carded out for the rainstorm from 2000 BST 5th to 0800 BST 12th July 2005 and WRF model is applied to simulate the precipitation process from 0800 BST 6th to 2000 BST 7th July 2005. Results show that： （ 1 ）The rainstorm process can be divided into two periods,nonlinear subcritical symmetric instability might be the main mechanism. （2） The strengthening of zonal disturbance wind component u and meridional v are respectively in advance of precipitation＇s enhancement, and the peaks of u and v disturbances as well as peaks of ageostrophic intensity and cold or warm air＇s peak indicate the precipitation peak which emerges after 12 or 24 h. （3）The space-time allocation among peaks of upper jet, lower jet, upper disturbance wind, lower disturbance wind and precipitation is revealed. （4）It is depicted that at earlier stage of rainfall, space-time allocations relate among upper level vorticity, divergence and lower level vorticity, divergence. The new physical mechanism that nonlinear subcritical symmetric instability stimulates rainstorm is shown by the above 4 points and the situation of vertical upward current.

关 键 词：非线性 亚临界对称不稳定 暴雨 扰动 

分 类 号：P458.121.1[天文地球—大气科学及气象学]