Understanding the initial conditions contributing to the rapid intensification of typhoons through ensemble sensitivity analysis  

作　　者：Yixuan Ren Lili Lei Jian-Feng Gu Zhe-Min Tan Yi Zhang 

机构地区：[1]Key Laboratory of Mesoscale Severe Weather,Ministry of Education,and School of Atmospheric Sciences,Nanjing University,Nanjing,China

出　　处：《Atmospheric and Oceanic Science Letters》2025年第2期36-42,共7页大气和海洋科学快报(英文版)

基　　金：supported by the National Natural Science Foundation of China[grant numbers 42192553 and 41922036];the Fundamental Research Funds for the Central Universities–Cemac“GeoX”Interdisciplinary Program[grant number 020714380207]。

摘　　要：While steady improvements have been achieved for the track forecasts of typhoons,there has been a lack of improvement for intensity forecasts.One challenge for intensity forecasts is to capture the rapid intensification(RI),whose nonlinear characteristics impose great difficulties for numerical models.The ensemble sensitivity analysis(ESA)method is used here to analyze the initial conditions that contribute to typhoon intensity forecasts,especially with RI.Six RI processes from five typhoons(Chaba,Haima,Meranti,Sarika,and Songda)in 2016,are applied with ESA,which also gives a composite initial condition that favors subsequent RI.Results from individual cases have generally similar patterns of ESA,but with different magnitudes,when various cumulus parameterization schemes are applied.To draw the initial conditions with statistical significance,sample-mean azimuthal components of ESA are obtained.Results of the composite sensitivity show that typhoons that experience RI in 24 h favor enhanced primary circulation from low to high levels,intensified secondary circulation with increased radial inflow at lower levels and increased radial outflow at upper levels,a prominent warm core at around 300 hPa,and increased humidity at low levels.As the forecast lead time increases,the patterns of ESA are retained,while the sensitivity magnitudes decay.Given the general and quantitative composite sensitivity along with associated uncertainties for different cumulus parameterization schemes,appropriate sampling of the composite sensitivity in numerical models could be beneficial to capturing the RI and improving the forecasting of typhoon intensity.针对台风强度特别是快速增强(RI)的预报难点,本文对2016年5个台风的6次RI过程应用集合敏感性分析(ESA),以分析有利于RI的初始条件.对于不同的个例和积云参数化方案,ESA获得的有利于台风RI的集合敏感性相似但量级存在差异.复合敏感性揭示了经历RI的台风所需的初始条件,其有更强的主环流,更显著的暖心及增加的低层湿度.ESA估计的集合敏感性随预报时长增加而减弱.通过采样复合敏感性可有望改进集合初始条件及台风强度预报.

关 键 词：TYPHOON Rapid intensification Ensemble sensitivity analysis Composite sensitivity 

分 类 号：P44[天文地球—大气科学及气象学]