1513号“苏迪罗”台风残涡强降水分布特征研究

Study on the distribution of torrential rain caused by residual vortex of typhoon Soudelor(1513)

运用自动站6 h降水资料和NCEP/NCAR的0. 25°×0. 25°再分析数据,着重分析了1513号台风"苏迪罗"及其残涡影响江苏期间强降水落区的分布特征,以及强降水落区与风场、涡散度、水汽通量散度等要素的对应关系。分析结果表明:强降水多分布在台风低层环流中心东北侧,风场围绕环流中心非对称分布造成辐合和正涡度在此处集中,进一步导致水汽在同一地区辐合,动力条件和水汽条件在同一地区叠加是强降水区位于环流中心东北侧的直接原因。单一等压面上的负散度和正涡度均可以在一定程度上指示出强降水站点位置,不同层次涡散度场的涵盖范围有所不同,三层算术平均后的涡散度较单一层次的指示性更为准确。"苏迪罗"登陆后在北上过程中接近中高纬西风带系统,环境风垂直切变逐渐增强且方向稳定,强降水落区基本位于850 h Pa至200 hPa间切变矢量的顺切变左侧,这一特征对判断登陆台风强降水落区具有一定的指导意义。

The distribution of torrential rain caused by residual vortex of typhoon Soudelor（ 1513）in Jiangsu Province during Aug. 10—11,2015 was researched in this paper based on 6-hour precipitation data and NCEP/NCAR 0.25°× 0.25°reanalysis data. The precipitation distribution and its relationship to wind,divergence,vorticity and moisture flux divergence were also analyzed. The results were as follows：the torrential rain was mostly located on north-east side to the lower circulation center,where convergence and positive vorticity were concentrated because of the asymmetric distribution of wind around the center.The superposition of dynamic conditions and water vapor conditions in the same area is the immediate cause of the torrential rain area located on the northeast of the circulation center. Both of the negative divergence and positive vorticity of single isobaric surface could indicate the torrential rain location.However,the coverage was varying when the isobaric surface changed. So the average value of the variables from three isobaric surfaces worked better. While Soudelor was approaching the weaterlies at mid-high latitudes,the vertical wind shear enhanced,with stable direction. The torrential rain was mostly located on down-shear left side of the shear vector between 850 h Pa and 200 hPa,which could be used tolocate the torrential rain caused by landed typhoon.