Buoyancy of convective-scale updrafts in the outer cores of sheared tropical cyclones  

作　　者：LI Qingqing FANG Qiaoxian 

机构地区：[1]Pacific Typhoon Research Center, Key Laboratory of Meteorological Disaster of the Ministry of Education, Nanjing University of Information Science and Technology [2]State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences

出　　处：《Atmospheric and Oceanic Science Letters》2019年第1期58-65,共8页大气和海洋科学快报（英文版）

基　　金：supported by the National Key Research and Development Program of China [grant numbers 2017YFC1501601 and 2015CB452803];the National Natural Science Foundation of China [grant numbers41475058,41730961,and 41875054];the Basic Research Fund of the Chinese Academy of Meteorological Sciences[grant number 2016Z003];the Top-notch Academic Programs Project of Jiangsu Higher Education Institutions(TAPP)

摘　　要：In this paper,the authors present the statistical characteristics of the buoyancy of outer-core convective-scale updrafts in numerically simulated sheared tropical cyclones(TCs).The total buoyancy is predominantly positive in weak-to-strong ambient vertical shears,whereas much of the total buoyancy under an extreme shear environment becomes negative.Thermal buoyancy positively contributes to the total buoyancy value.For weakly and moderately sheared TCs,the updraft buoyancy is statistically significantly stronger downshear but smaller upshear.Such a downshear preference of strong buoyancy becomes less evident as the shear magnitude increases.The total buoyancy of updrafts shows a decreasing tendency with radius.Both thermal and dynamic buoyancy do not significantly correlate with vertically averaged vertical mass fluxes.This also leads to no significant correlation between the total buoyancy and vertical mass fluxes of outer-core updrafts.通常认为局地浮力与对流活动息息相关。本文统计分析了不同强度垂直风切变影响下热带气旋外核区对流尺度上升运动的浮力特征。研究发现,弱至中等强度的垂直风切变环境下,顺切变象限的浮力大于逆切变象限的浮力,顺切变象限的总浮力随风切变的增大而减小。而在极端强度的风切变影响下,大部分总浮力为负值。热力浮力、动力浮力与上升运动垂直质量输送没有明显相关性,因此总浮力和垂直质量输送也无显著相关性。上述结果加深了我们对热带气旋外核区对流发生发展过程的物理认识。

关 键 词：Tropical cyclone vertical wind shear outer core UPDRAFT BUOYANCY 

分 类 号：P[天文地球]