摘要
利用再分析资料和红外云图普查西北太平洋具有非典型对流分布特征(对流集中于逆切变一侧)的快速增强(RI)台风个例。通过与具有典型对流分布(对流集中于顺切变一侧)的缓慢变化个例(noRI)对比分析后发现,RI组在风切方向左侧拥有更强的地表潜热通量高值中心。为进一步探讨可能机制,本文选取非典型对流台风利奇马进行敏感性数值试验。诊断结果表明,风切方向左侧较高的地表潜热通量有利于建立该地区对流不稳定。同时,地表潜热通量会通过“边界层熵恢复”机制削弱“通风效应”作用。在高层东风切变下,当对流从顺切变一侧移动至逆切变一侧,对流活动在高地表潜热区域可以得到增强,从而激发出强的上层出流通道;而出流通道的建立(出流阻挡机制)可以抵抗环境东风流,从而削弱垂直风切强度,帮助台风恢复直立发展。
In this study,RI(rapid intensification)tropical cyclones with atypical convection(upshear concentrated convection)in the Northwest Pacific were screened using reanalysis data and infrared cloud images.A group of slow intensification(noRI)typhoons with typical convection(downshear concentrated convection)was gathered for comparison.The RI group has a stronger center of surface latent heat flux on the left side of the VWS(vertical wind shear)direction.To further explore possible mechanisms,the atypical convection case Lekima was selected for sensitivity numerical experiments.Diagnostic results indicate that surface latent heat flux on the left side of the VWS direction helps establish convective instability in the region.Consequently,the influence of the“ventilation effect”is weakened because of the“boundary layer entropy recovery”mechanism caused by surface latent heat flux.Under easterly VWS,convection activity can be enhanced in regions with high surface latent heat flux during the transition from downshear to upshear,thereby stimulating strong upper outflow channels.The establishment of outflow channels(outflow blocking mechanism)can resist environmental easterly flow,weakening the strength of VWS and allowing typhoons to develop vertically.
作者
沈上骐
黄绮君
葛旭阳
SHEN Shangqi;HUANG Qijun;GE Xuyang(Key Laboratory of Meteorological Disaster of Ministry of Education(KLME)/Joint International Research Laboratory of Climate and Environment Change(ILCEC),Nanjing University of Information Science and Technology,Nanjing 210044;Shanghai Typhoon Institute,Shanghai 200030;Shanghai Ecological Meteorology and Remote Sensing Center,Shanghai 200030)
出处
《大气科学》
北大核心
2025年第3期752-766,共15页
Chinese Journal of Atmospheric Sciences
基金
国家自然科学基金项目U2342202,42175003
上海台风基金项目TFJJ202402
上海市协同创新专项资金(创新协调)项目CXXT-2023-06。
关键词
热带气旋
快速增强
高层切变
出流
地表潜热通量
Tropical cyclone
Rapid intensification
Upper vertical shear
Outflow
Surface latent heat flux
