季风槽中热带气旋生成初期扰动的扰动动能收支分析  

Kinetic Energy Budegt Analysis of Tropical Cyclogenesis Precursors in the Monsoon Trough

作　　者：段晶晶[1,2] 吴立广[1] 

机构地区：[1]南京信息工程大学气象灾害省部共建教育部重点实验室,南京210044 [2]宁波市气象台,浙江宁波315012

出　　处：《气象科学》2016年第2期141-148,共8页Journal of the Meteorological Sciences

基　　金：国家自然科学基金资助项目(41275093);江苏省特聘教授项目

摘　　要：热带气旋总是发生在天气尺度扰动中,本文利用NCEP/NCAR提供的FNL资料,选取了2004年8月11日—9月10日期间季风槽中5个热带气旋生成初期扰动,通过计算动能收支分析这些初期扰动的发展。其中4个热带气旋都是生成在向西北方向传播的天气尺度波列的气旋性环流中,气旋性环流可以和呈东北—西南方向倾斜西传的MRG波的逆时针环流耦合。动能收支计算表明,初期扰动动能在热带气旋生成前12~72 h不断增加,扰动位势通量的辐合对扰动动能增长起了主要作用。在季风槽东端的合流区时,能量聚集项有重要作用,随着扰动移入季风槽内,低频纬向风切变项成为能量增加的一个重要来源。Sarika生成于季风槽西撤阶段,非线性作用项对扰动发展起了关键作用。Tropical cyclones always occur in a synoptic-scale disturbance. By using NCEP/NCAR FNL data, tropical cyclogenesis precursors in the monsoon trough from 11 August to 10 September 2004 were chosen. Through calculating the kinetic energy budget, we analyzed the development of the tropical cyelogenesis precursors. Aside from Chaba, others all formed in the cyclonic circulation of the northwest- ward-propagating synoptic-seale wave trains. The cyclonic circulation can couple with the northeast- southwest-titled anticlockwise circulation of the westward-propagating MRG wave. Kinetic energy budegt analysis reveals that kinetic energy of tropical cyclogenesis precursors increased before 12-72 hours prior to the formation of the tropical depression. Local convergence of the eddy geopotential flux was the domi- nant term. When the precursor first appeared at the far eastern end of the monsoon trough, energy accu- mulation was also a main factor for disturbance development. As the disturbance moved northwestward and entered the monsoon shear region, barotropic energy conversion by the meridional gradient of the basic zonal flow was indeed another important energy source. For the case of Sarika, it formed when the MT westward retreated. The nolinear term played another important role for this disturbance development.

关 键 词：热带气旋生成的初期扰动 MRG波 天气尺度波列 能量分析 

分 类 号：P444[天文地球—大气科学及气象学]