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西北太平洋迅速增强热带气旋内核区微波亮温特征

发表时间:2018-06-29  浏览量:683  下载量:80
全部作者: 张宸,袁铁
作者单位: 兰州大学大气科学学院
摘 要: 利用美国国防气象计划(Defense Meteorological Satellite Program,DMSP)卫星专用微波成像仪(special sensor microwave imager,SSM/I)和热带降雨测量任务(tropical rainfall measuring mission,TRMM)卫星微波成像仪(TRMM microwave imager,TMI)的85 GHz与37 GHz微波资料分析西北太平洋热带气旋(tropical cyclone,TC)的不同强度变化阶段,特别是迅速增强(rapid intensification,RI)前后内核区微波亮温的特征。根据TC未来24小时的强度变化将TC分为迅速衰减(rapidly weakening,RW)、慢衰减(slow weakening,SW)、成熟(neutral,N)、慢增强(slow intensification,SI)和RI五个阶段。结果表明,TC内核区中对流活动虽强,但85 GHz和37 GHz的极化修正温度(polarization corrected temperature,PCT)(简称PCT85和PCT37)仍是以弱散射信号为主。RI阶段与其他强度变化阶段相比,内核区小于250 K的PCT85和小于270 K的PCT37主要集中在风切变左侧,其中190~225 K的PCT85和260~270 K的PCT37在风切变左右两侧的面积差较为明显。此外,RI发生前内核区190~225 K、225~250 K的PCT85和260~270 K的PCT37的面积分别不超过总内核区的30%、50%和60%,随着RI的发生,亮温集中区域移动至TC中心周围,形态趋于对称。对内核区PCT85最小值小于190 K和PCT37最小值小于250 K的分析表明,RI阶段TC内核区强对流的出现频率(约71%)高于其他强度变化阶段,且其中大部分出现在RI发生12小时以前。
关 键 词: 大气科学;热带气旋;迅速增强;微波亮温;内核区对流
Title: Characteristics of inner-core microwave brightness temperature in rapidly intensifying tropical cyclones over northwestern Pacific
Author: ZHANG Chen, YUAN Tie
Organization: College of Atmospheric Sciences, Lanzhou University
Abstract: The passive microwave data (85 GHz and 37 GHz) from the special sensor microwave imager (SSM/I) on board the Defense Meteorological Satellite Program (DMSP) satellites and tropical rainfall measuring mission (TRMM) microwave imager (TMI) is used to investigate the brightness temperature characteristics of tropical cyclone (TC) inner-core region over the northwestern Pacific during different intensity change categories, especially rapid intensification (RI). According to the intensity changes in 24 hours, TCs are divided into five intensity categories, such as rapidly weakening (RW), slowly weakening (SW), neutral (N), slow intensification (SI) and RI. The results show that, although the TC inner-core convection is strong, the weak scattering signals are still dominated from the polarization corrected temperature (PCT) at 85 GHz and 37 GHz. PCT of 85 GHz below 250 K and PCT of 37 GHz below 270 K are mainly located at the wind shear left in the inner-core region in rapidly intensifying TC compared with the TC during other intensity change categories, and there are significant area differences of PCT of 85 GHz in 190-225 K and PCT of 37 GHz in 260-270 K between wind shear left and shear right in inner-core region. Meanwhile, the areas of PCT of 85 GHz in 190-225 K and 225-250 K, PCT of 37 GHz in 260-270 K account for less than 30%, 50% and 60% of total inner-core region before RI onset, respectively. After RI onset, microwave brightness temperature concentrates toward TC center, and appears a symmetrical pattern. The analyses of minimum PCT of 85 GHz below 190 K and minimum PCT of 37 GHz below 250 K indicate that the occurance frequency of strong convection in inner-core region during RI (about 71%) is higher than that during other intensity categories, and most of strong convections occur before 12 hours of RI onset.
Key words: atmospheric sciences; tropical cyclone; rapid intensification; microwave brightness temperature; inner-core convection
发表期数: 2018年6月第12期
引用格式: 张宸,袁铁. 西北太平洋迅速增强热带气旋内核区微波亮温特征[J]. 中国科技论文在线精品论文,2018,11(12):1240-1254.
 
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