利用多普勒雷达数据分析中国华东地区登陆台风轴对称降水特征  

An analysis of spatial and temporal variations in the axisymmetric precipitation structure associated with typhoons making landfall on the southeastern coast of China based on the Doppler radar data

作　　者：吴丹[1] 赵坤[1] 余晖[2] 王明筠[1] 

机构地区：[1]教育部国家中尺度灾害性天气重点实验室南京大学大气科学学院,南京210093 [2]上海台风研究所,上海200030

出　　处：《气象学报》2010年第6期896-907,共12页Acta Meteorologica Sinica

基　　金：国家重点基础研究发展计划项目(2009CB421500);国家自然基金项目(40505004和40333025);国家重点机理研究发展项目(973:2004CB18301);上海台风研究基金(2006STA012);国家科技部科研院所社会公益研究专项(2005DIB3J104)

摘　　要：利用中国新一代多普勒雷达网温州雷达和台湾气象局五分山雷达资料、地面自动站降水资料,分析2004—2007年登陆中国华东地区的6个台风从登陆前18小时至登陆后6小时的降水结构时空变化特征。环状平均回波分析显示,在台风离陆地较远时,轴对称降水径向廓线呈双峰结构,最大降水位于台风眼端处,降水次大值位于台风外围雨带处。台风强度越强,最大降水越强,且离台风中心的距离也越近。当台风接近登陆时,其内核区降水有增强的趋势,从登陆前6小时至登陆时,各台风内核区平均降水率的增强倍率在1.3—3.2,且外围降水随时间向台风中心收缩,内缩速率随台风强度增强而减慢。台风登陆后,台风眼被降水填塞,强度快速减弱,同时降水持续内缩,内核区总降水逐渐衰减。此外本文还建立了一个登陆前台风轴对称降水径向廓线模型,该模型能定量地描述降水廓线的双峰结构,模拟结果与实际雷达观测降水廓线的的均方根误差最小为0.46 mm/h,最大为5.3 mm/h。This study investigated temporal and spatial variations in the precipitation structure within 300 km radius from typhoon center by using the reflectivity data taken from the Doppler radars located in Wenzhou（CINRAD WSR-98D） and Wufenshan, Taiwan,China.Six typhoons making landfall along the southeastern coast of China in the years of 2004 - 2007 have been selected to examine changes in the precipitation distribution from 18 h before landfall to 6 h after landfall.The axisymmetric component of typhoon rainfall,represented by the radial distribution of the azimuthally mean reflectivity,reveals that the maximum rainfall is located in the eyewall and a secondary maximum rainfall is in the rainband outside from 9 to 18 h before landfall. With increasing storm intensity,the maximum rainfall rate increases while its radius from the typhoon center decreases. When typhoons are approaching the coast,the mean rainfall rale in the inner-core region increases abruptly,accompanied with the rapid contraction of the out-ring precipitation toward typhoon center.The highest intensification factor of the mean rain rate in the inner-core of the six typhoons reaches 3.2.The peripheral rainbands contract to typhoon center simultaneously,and the rates of contraction decrease with typhoon intensifying.After typhoon landfall,the eye is filled by rain and the intensity decreases quickly with the precipitation shrinking continuously.As a result,the amount of rainfall in the inner-core attenuates gradually. Finally,a model was proposed in this paper to fit the observed precipitation curve before typhoon landfall.This model is able to quantitatively describe the profile of the azimuthally mean rain of typhoon,and reveal the characteristic of two-peak of the profile.The maximum of the RMSE between the observed curve and the simulative result was 5.3 mm/h while the minimum was only 0.46 mm/h,suggesting that the model can well fit the real outline of typhoon precipitation.

关 键 词：登陆台风 轴对称分量 降水分布 

分 类 号：P458.124[天文地球—大气科学及气象学]