派比安台风(0606)登陆期间雨带中尺度结构的双多普勒雷达分析  

The Rainband Structure of Typhoon Paibian(0606) during Its Landfall from Dual-Doppler Radar Observations

作　　者：赵坤[1] 周仲岛[2] 胡东明[3] 潘玉洁[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系,南京210093 [2]台湾大学大气科学系 [3]广州中心气象台,广州510080

出　　处：《南京大学学报（自然科学版）》2007年第6期606-620,共15页Journal of Nanjing University（Natural Science）

基　　金：国家自然基金(40505004;40333025);国家重点基础研究发展规划项目(973:2004CB18301)

摘　　要：2006年8月3日派比安台风(0606)接近登陆时,在距离台风中心东北180km处有一强螺旋雨带生成,并随台风往陆地方向移动.本研究利用位于广州和深圳的新一代天气雷达所收集到的双多普勒雷达资料,分析该螺旋雨带的回波结构和中尺度风场,并探讨其维持机制.雷达回波分析显示,雨带由多个对流单体组织成西北—东南走向的带状结构,长约200km,宽约35km.同过去研究中台风雨带气流结构呈准二维相比,该雨带在成熟时期的气流结构呈明显的三维特征.从雨带上游至下游,沿雨带方向风速显著减弱,而跨雨带方向风速则明显加强.在雨带上游,雨带内侧为外流,而雨带外侧3km以下为内流.其中2km以下气流进入雨带时逐渐减速并在雨带内形成强辐合,部分内流转为倾斜往外的气流.1km以下,部分内流穿过雨带的强回波中心与雨带内侧的外流在雨带内边缘形成另一强辐合区.在雨带下游,在5km高度以下雨带内外均侧为内流,其中2km以下气流从雨带外部进入雨带时先加速,随后逐渐减速,在雨带内侧边缘形成最强的辐合上升运动后,随高度向外倾斜并在雨带外部形成下沉,部分下沉气流转为内流重新进入到雨带.由于雨带上、下游分别位于海洋和陆地上,因此海陆摩擦差异是造成雨带上、下游气流结构差异一个重要原因.而另一个原因是雨带上、下游同以台风中心为圆心的圆周切线间夹角不同.此外,雨带内的气流也表明由倾斜上升在雨带外侧下沉转化成的内流,对于雨带上、下游内流的加强和维持具有重要作用.In this study, the dual-Doppler observations are used to investigate the mesoscale structure of the spiral rainband of typhoon Paibian （0606） during its landfall in Guangdong Province. The rainband is 200 km long and 35 km wide. Its location is 180 km to the northeast of the storm center and its orientation is from northeast to southwest. The rainband here exhibits distinct three-dimensional features, compared with previously documented typhoon rainbands, which are often characterized by two-dimensional mesoscale structure. From the upband to downband, the alongband wind decreases, but on the other hand, the crossband wind increases. At the upband, the inflow enters the rainband at Z〈2 km from outside rainband and produces a maximum updraft inside rainband, part of which penetrates the heavy precipitation region to reach the inner edge of the rainband and converges with the outflow from inner side of the rainband at Z〈1 km. In contrast, the inflow intensifies and deepens at the downband with its depth reaching about 5 km in the rainband region. When the low-level inflow enters the rainband at Z〈 2 km, it gradually decelerates and produces a slantwise updraft at inner edge of the rainbarid. Since the upband and downband are covered over ocean and land, the frictional difference between land and ocean may be an important factor causing such a flow variation along the rainband. The cross angle of rainband to circles around the storm center is another possible factor. It is also noted that a return flow from the slantwise updraft feeds back the inflow both at the upband and downband, which plays an important role to maintain the rainband.

关 键 词：双多普勒雷达 螺旋雨带 三维特征 

分 类 号：P458[天文地球—大气科学及气象学]