岛屿地形对涡旋Rossby波传播影响的研究  

Island-like Topographic Effects on the Propagation of Vortex Rossby Waves

作　　者：余锦华[1] 谈哲敏[1] 

机构地区：[1]南京大学中尺度灾害性天气教育部重点实验室大气科学系

出　　处：《南京大学学报（自然科学版）》2007年第6期597-605,共9页Journal of Nanjing University（Natural Science）

基　　金：国家自然科学基金(40333031;40333025);江苏省高校自然科学基础研究项目(07KJBB170065)

摘　　要：首先在静止基本状态下,从线性f平面极坐标浅水方程出发,利用WKB方法求解方程,在理论上给出了一类由于地形βeff作用引起的Rosbby波的传播特征解,此类Rossby波类似于涡旋Rossby波(VRW),其中地形βeff作用与台风涡旋基态的垂直相对涡度径向梯度作用相似,此分析解可帮助理解地形对涡旋Rossby波的影响作用.在此基础上,利用一个高分辨率的浅水模式具体讨论了圆形、类似于台湾岛屿椭圆地形对VRW传播以及结构特征变化的影响.结果表明,地形对VRW的传播速度,台风内区的非对称结构的变化均构成影响.当台风位于地形东南一定距离处,与无地形相比,涡量向内向外传播均增强,扰动能量增大,涡量环绕地形中心沿等高线顺时针方向移动,局域风速增大,并形成尺度为几十公里左右的强局域风速区,平均风速减小.Firstly, with the WKB method the linear orographic-Rossby wave solution is obtained in a linear shallow-water model on an f-plane. The analytic solution is similar to the propagating vortex Rossby waves （VRW） due to the topographic βeff takes effects resemble with the radial derivative of basic-state vertical vorticity of tropical cyclone. These results are helping to understand for the effect of terrain on the VRW. Secondly, a high resolution shallow-water model is designed to study the effects of circular and island terrain similar to Taiwan on the propagating of VRW and the tropical cyclone intensity changes. The results show that the effects are made up on the propagating speed of VRW, asymmetry structure in the inner-core and intensity of tropical cyclone. In comparison with no terrain, the topographic effects make the intensity of the inward and outward propagation of vorticity radically strengthened, and the vortex following a clockwise island-circulating path, as well as the asymmetry structure in inner-code of tropical cyclone more remarkable. Also the terrain-induced propagation of VRW leads to the formation of a local maximum wind speed in the inner region with 10km scale and the maximum mean azimuthally tangential wind spun down.

关 键 词：岛屿地形 涡旋ROSSBY波 涡旋移动 

分 类 号：P4[天文地球—大气科学及气象学]