Measurement study on wind characteristics of Typhoon Kalmaegi on the sutong bridge

The Sutong Bridge, a cable-stayed located in the southeast coastal area of China, is vulnerable to the Pacific typhoons. From the data measured by two 3D ultrasonic anemometers at the height of 76 m and 306 m, the wind characteristics (including 10-minute mean wind speed and direction, turbulence intensity and gust factor, power spectral density and integral scale of turbulence) of Typhoon Kalmaegi are analyzed The comparison of 10-minute mean wind velocity from the two anemometers validates the reliability...     

Use of the advanced microwave sounding unit data to improve typhoon prediction

The effects of incorporating the advanced microwave sounding unit(AMSU-A)data with a modified Zhu-Zhang-Weng vortexbogussing algorithm on typhoon prediction are examined through the use of the PSU/NCAR Mesoscale Model version 5(MM5).The AMSU-A data contain the vertical distribution of the retrieved temperature from satellite brightness temperature, with the geopotential height and wind fields derived through a series of statistical and diagnostic calculations.The advantages of the modified vortexbogussing algorithm include the incorporation of realistic asymmetric typhoon structures,the balanced dynamics with the background field,the easiness to implement and the efficient computations.To test the efficiency of this vortex-bogussing algorithm,the Typhoon Dan event in 1999 is simulated by incorporating the derived AMSU-A fields into the initial conditions of the MM5 modeling system.Results show significant improvements in the track and intensity of the storm, as compared to the simulation without the AMSU-A data.Therefore,this modified vortex-bogussing algorithm can be easily implemented on any typhoon modeling system,which will improve the real-time forecast of tropical cyclones.     

降水条件下台风的定常运动和螺旋斑图

在牛顿第二运动定律的基础上,在垂直方向的运动方程中加入了扰动降水量一项,并讨论了加入这一项的合理性和物理意义.重点考虑了在降水条件下台风的运动特征,同时求得了三维定常流场中的水平速度,其中的三维流场构成了物理空间的一个非线性自治动力系统.研究表明:根据台风运动的定常解,台风的下层中心是低气压且是正垂直涡度(气旋式涡度)和水平辐合,上层中心是高气压(反气旋式涡度)和水平辐散.根据台风自治动力系统所获得的两个鞍-焦点很好地说明了台风的螺旋斑图,下层空气螺旋向内,引起台风中心附近的上升运动,上层空气螺旋向外引起台风外围的下沉运动,这些都与实际台风结构相似.文中阐明:在考虑降水量的影响后,台风仍然具有螺旋斑图的特征.     

台风“梅花”近地风剖面变化研究

基于10、20、30和40m高度处台风"梅花"影响下的上海浦东地区近地风现场实测数据,主要研究了平均风速、湍流度和阵风因子随高度的变化规律.结果表明,通过公式计算得到的边界层高度随平均风速的增大而增大,平均值为2 063m,远远大于我国规范(GB50009—2001,2002)规定的B类地貌下的边界层高度(350m).当平均风速较大时,大气稳定度参数z/L随平均风速变化较小,基本在区间[-0.1,0.1]内波动,此时大气近似趋于中性.指数率、对数率和Deaves-Harris模型与平均风速实测剖面均吻合较好.参考ASCE7-10中湍流度剖面的表达形式,通过拟合得到了纵向、横向和竖向湍流度随高度变化的经验表达式.另外,对实测阵风因子随高度的变化进行了拟合,拟合结果可以为今后工程设计提供参考.     

台风载荷作用下输电塔线体系时程分析及补强措施

为研究±800 kV输电线路所使用的横担较长的铁塔在受到台风载荷作用时的时程响应分析,通过建立三塔两线有限元模型,基于风速不随高度变化的Von Karman谱,利用谐波叠加法生成了基准风速为50 m/s的风速时程,应用模拟的台风载荷进行时长为50 s的时程分析,共分析了风载荷45°、60°、90°作用下塔线体系的三种情况。仿真结果显示,在45°和60°风作用下,铁塔中部、塔头和塔身连接的平口处应力超过屈服强度,导、地线挂线板处所受应力也超限,铁塔在90°风作用时,塔身腰部主材和塔腿主材应力也超过屈服强度。要预防台风对铁塔的破坏,应该从上述三个部位对铁塔进行补强,在塔腿及塔腰之间增加水平材是一种有效的加固措施。     

基于多卫星和Argo浮标观测海洋上层对台风婷婷的响应

利用多卫星平台和Argo浮标观测资料,分析研究了2004年台风婷婷(Tingting)引起海洋上层温盐结构和叶绿素a浓度的时空变化特征.结果发现,台风婷婷过境时沿着其路径诱发强烈的上升流,混合层内海水混合加剧,冷涡加强,出现了大范围的海表温度降低和叶绿素a增加现象.台风前的冷涡区域,出现大面积的"冷斑"和"藻华带",且维持时间更长;而在台风前的暖涡区域内,则生物物理响应不明显.因此,先前的海洋环境对于台风引起的上层生物物理响应具有重要意义.     

Diagnostic analysis of the asymmetric structure of the simulated landfalling typhoon “Haitang”

The landfalling processes of Typhoon ＂Haitang＂ near Lianjiang of Fujian Province of China from 00 UTC 19 to 12 UTC 20 July 2005 were reproduced by using the nesting non-hydrostatic WRF model and data assimilation technology （Level II Doppler radar data of Changle of Fujian Province are assimilated to the simulation every one hour from 01 to 06 UTC 19 July 2005）. The mesoscale structure and evolution of the typhoon before, during, and after its landfall were discussed. The simulation data show that the assimilation exper- iment with the high temporal-and-spatial-resolution radar radial velocity and reflectivity data can produce much better simulation of the typhoon track, intensity evolution and landfalling location than the control experiment without assimilating radar data. By using the assimilation experimental data, the mesoscale fine-mesh structure and evolution before and after typhoon landfall were analyzed. Because of the influence of sea-land thermodynamic difference, two asymmetric convective regions were located at ocean and land, respectively. To better understand and investigate the asymmetric-structure characteristics of the landfalling typhoon, several dynamical diagnostic tools, the helicity （H）, the moist potential vorticity （MPV）, the convective vorticity vector （CVV）, the moist vorticity vector （MVV）, which are associated with the development of strong convections, are introduced. Further analysis illuminates that the distribu- tions of these physical diagnostic parameters are totally asymmetric, and subsequently, the associated convections also show distinct asymmetry.     

登陆台风路径与降水分析

首先利用1979—2002年台风年鉴上的热带气旋纪要表进行分析，总结热带气旋的登陆数据，并根据热带气旋路径图归纳出线性、左折、右折三种路径的登陆热带气旋。利用欧洲中心每天4次（6小时预报）的总降水资料，将热带气旋作为一个整体来研究探讨它在海洋和陆地上的降水分布和演变特征，尤其是台风路径与降水分布之间的关系，弥补以往对热带气旋降水的研究只局限于陆地降水的不足。     

云娜台风加强及特大暴雨过程的多普勒速度场特征研究

浙江省温州市CINRAD-SA雷达站因其较好的地理位置,详细探测了在有效观测范围内云娜台风发展、演变、近海加强加速、登陆及西行衰亡的全部过程。利用其获取的强度场与速度场资料,结合台风定位资料及自动站雨量资料,分析了台风加强及特大暴雨时段的多普勒雷达强度场、速度场特征,发现多普勒雷达能捕捉到远距离台风的加强信息。这次台风造成了浙江省多场暴雨过程,多普勒速度场资料揭示了在台风这一暖心低压的背景下,高空西南急流的脉动、高空辐散的加强、台风北侧弱冷空气的触发与特大暴雨的良好对应关系。     

台风“莫兰蒂”（1010）近海加强原因分析

本文应用NOAA热带风暴风场分析资料和NCEP资料分析＂莫兰蒂＂台风近海加强的原因,结果表明：中心附近环境风垂直切变小、高的暖核高度、越赤道气流输送的暖湿水汽、弱冷空气从西北面渗漏至气旋中心外围等因素引发＂莫兰蒂＂近海加强,弱的环境风垂直风切和高的暖核高度是最主要的因素。