T-TREC方法反演登陆中国台风风场结构  

The T-TREC technique for retrieving the winds of landfalling typhoon in China

作　　者：王明筠[1] 赵坤[1] 吴丹[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

出　　处：《气象学报》2010年第1期114-124,共11页Acta Meteorologica Sinica

基　　金：国家自然基金(40505004和40333025);国家重点基础研究发展计划项目(973:2009CB421502);国家重点机理研究发展项目(973:2004CB18301);上海台风研究基金(2006STA01-2);国家科技部科研院所社会公益研究专项(2005DIB3J104)

摘　　要：在传统的基于天气雷达反射率因子的相关方法跟踪回波运动(TREC)技术的基础上,本研究发展出适用于台风环流反演的T-TREC方法。同传统的TREC技术相比,T-TREC根据台风环流呈逆时针方向旋转的特征,利用雷达观测资料客观选取台风中心,选取扇形网格单元,在以台风中心为原点的极坐标系下进行逆时针方向回波追踪。同时,该方法也利用雷达径向风资料客观选取切向的搜索范围并建立风场相关矩阵,以减少主观设定搜索区域造成的误差。通过利用中国新一代天气雷达网(CINRAD WSR-98D)观测的登陆台风桑美(0608)资料对方法进行验证,结果表明T-TREC方法可以更加准确估计强台风环流,反演的径向风平均误差小于4 m/s。其中径向风信息的引入明显提高了反演风场精度,特别是改善了在眼墙区因回波结构较均匀造成的风场低估。当台风靠近陆地时,因地物回波以及台风环流与地形相互作用激发对流的影响,使得低层风场反演误差增加。文中也探讨了台风中心、搜索网格单元大小等因子对反演精度的影响,结果显示,反演结果对于中心定位比较敏感,中心位置偏移4 km将造成反演的径向风平均误差增加约10%。而搜索单元大小对反演结果影响和台风尺度相关,若台风尺度较小,则较小的搜索单元反演效果较好。In this study,an extension of TREC（Tracking Radar Echo by Correlations） technique,named Typhoon Circulation TREC （T-TREC）,is developed.The TREC analysis is performed on a polar coordinate centered on the tropical cyclone（TC） eye using arcshaped correlation cells and arc-shaped search area with a shorter dimension in the radial direction and a longer dimension in the azimuthal direction in order to reflect the fact that the tangential component of typhoon circulation is usually much larger than its radial component.The search for the best correlation match is limited to the cyclonic direction for TCs in the Northern Hemisphere on the basis of the cyclonic circulation characteristics of TCs.And the typhoon center is determined objectively by the weak echo finding technique. In addition to reflectivity data,the Doppler radar radial velocity is incorporated to estimate the search range and create a velocity correlation matrix in order to alleviate the uncertainty of tracking reflectivity only. By applying the T-TREC algorithm to the data of Landfalling Typhoon Saomai（0608） collected by China new generation radar the Weather Surveillance Radar - 1998 Doppler（CINRAD WSR-98D） on the southeast coast of China,it can be seen that this new method can estimate the typhoon circulation more accurate than TREC method,and the mean radial velocity errors in landfalling typhoon are less than 4 m/s.The incorporation of radial velocity information could distinctively improve wind retrievals of intense typhoon,especially reducing the underestimation caused by fairly uniform reflectivity patterns in the vicinity of the eyewall and rainband outside.It is noted that the error rates of retrieved wind at low levels increased partly due to the interference of ground clutter and the new convection forced by the interaction of the typhoon circulation with the terrain,as the typhoon approached the land.The quantitative evaluation of the influence of typhoon center and cell size on the wind estimation demonstrates that the

关 键 词：登陆台风 雷达回波相关跟踪法 多普勒雷达 

分 类 号：P412.16[天文地球—大气科学及气象学]