广西钦州湾台风“启德”风场特征实测研究

利用在广西钦州湾设立的一座55m高测风塔上的超声风观测仪器,收集到台风"启德"影响过程的脉动风数据,对湍流脉动风场特征参数进行了分析研究,结果表明:(1)台风"启德"影响期间观测到的最大风速为26.0m·s-1,过程风向由北风转向东北风、东风,过程转向幅度最大为157°,风攻角绝大部分在±3°范围内;(2)三维方向的湍流强度平均值比值为1:0.73:0.50,湍流积分尺度分别为313m、224m、163m,表现为均匀平稳的湍流变化过程;(3)湍流功率谱在惯性副区内基本满足-5/3律,其斜率随着风速的增大有减小的趋势。

Sensitivity of WRF simulated typhoon track and intensity over the South China Sea to horizontal and vertical resolutions

To determine the grid resolutions of the WRF model in the typhoon simulation,some sensitivity analysis of horizontal and vertical resolutions in different conditions has been carried out.Different horizontal resolutions(5,10,20,30 km),nesting grids(15 and 5 km),different vertical resolutions(35-layers,28-layers,20-layers)and different top maximum pressures(1 000,2 000,3 500,5 000 Pa)had been used in the mesoscale numerical model WRF to simulate the Typhoon Kai-tak.The simulation results of typhoon track,wind speed and sea level pressure at different horizontal and vertical resolutions have been compared and analyzed.The horizontal and vertical resolutions of the model have limited effect on the simulation effect of the typhoon track.Different horizontal and vertical resolutions have obvious effects on typhoon strength(defined by wind speed)and intensity(defined by sea level pressure,SLP),especially for sea level pressure.The typhoon intensity simulated by the high-resolution model is closer to the real situation and the nesting grids can improve computational accuracy and efficiency.The simulation results affected by vertical resolution using 35-layers is better than the simulation results using 20-layers and 28-layers simulations.Through comparison and analysis,the horizontal and vertical resolutions of WRF model are finally determined as follows:the two-way nesting grid of 15 and 5 km is comprehensively determined,and the vertical layers is 35-layers,the top maximum pressure is 2 000 Pa.

南海夏季风对台风“启德”极端降水影响的数值模拟

本文为研究台风“启德”极端降水的成因,模拟了南海夏季风减弱后台风“启德”的路径、强度、雨带位置、降水强度等。结果表明,夏季风削弱后,南海地区的西南季风受到抑制,台风强度减弱,台风范围内降水强度总体减弱,台风雨带偏南,因此南海夏季风强度减弱不利于极端降水的产生。降水模拟过程中发现,降水强度的减弱在整个模拟试验时间周期内,表现为非峰值强度减弱明显,而峰值强度不明显减弱。进一步分析了台风降水的逐小时演变特征和台风路径特征。结果表明,控制试验与敏感性试验模拟台风登陆在时间上存在时间差,与台风降水的逐小时变化峰值出现的时间差基本对应。这说明可能台风登陆过程的其他复杂因素导致夏季风减弱后台风登陆降水不表现出明显减弱。而非登陆过程,减弱夏季风对台风降水有减幅作用。

台风“启德”登陆过程中近地风场特征

通过对台风过程的风速及风向、阵风因子、湍流度和风速谱等参数的分析,研究了台风"启德"登陆时的近地风场特性.结果表明:台风"启德"的最大瞬时风速达到20m/s,10min最大平均风速为16m/s,台风登陆前,风速及风向脉动变化很大;台风登陆后,湍流度及阵风因子明显减小;风速变大,湍流度和阵风因子有减小的趋势.

启德河——“共构、共建、共享”的人文理念

作为东九龙连接启德的自然通廊,启德河起着重现人文景观的纽带作用。以"共构、共建、共享"人文理念为指导,通过众多非政府组织的协作,以及学生和专业人士的意见参与,香港特区政府基于实际考虑而提出的政策,使启德河逃脱被覆盖的命运,令生态重临,人文景观再现。"人自地而生,地因人而活"这种互为因果的关系,正说明了文化生态与本土生活密不可分的共存关系,启德河转变为"生态河"的启示和经验可为其他区域借鉴。