台风Krovanh(0312)及其台风浪的数值模拟

NUMERICAL SIMULATION OF TYPHOON KROVANH AND TYPHOON-INDUCED OCEAN WAVES

关键词:  中尺度气象模式  海浪模式  数值模拟

Key words:  mesoscale meteorological model  wave model  numerical simulation

摘要:

利用美国NCAR/PSU的中尺度气象模式MM5和第三代海洋风浪模式WAVEWATCH III(WW3)对台风Krovanh(0312)及其引起的台风浪过程进行了数值模拟试验。与观测对比表明:利用三维变分同化技术改进初始场后,MM5模式能够较好地模拟台风的登陆过程,强度变化及移动路径。利用MM5输出的10m风场驱动海浪模式,WW3模式能较好地模拟出海浪中心的位置,但强度较TOPEX/Poseidon(T/P)卫星高度计观测的浪高偏低23%~33%;台风登陆时模拟的风暴潮的强度和空间分布特征与实际海况较为一致。对风场和海浪的分析表明:在空间分布上,海浪分布与台风的中心位置和强度密切相关,当最大风速中心位于台风的右方时,有效浪高中心出现在大风区的下风方;在时间变化上,深水风浪阶段有效浪高相对于海表面最大风速有明显的滞后相关,以滞后4个小时的相关系数最高,达到0.53,之后相关系数逐渐变小,而浅水风浪阶段,由于相对水深变浅,虽然风速少变,但有效浪高随相对水深的减小而迅速增大,登陆时有效浪高迅速减小,与以往研究的结果相一致。

Abstract:

The mesoscale meteorological model MM5 developed by NCAR/PSU and the third generation wind wave model WAVEWATCH Ⅲ(WW3)were used to simulate Typhoon Krovanh(0312)and typhoon-induced waves.Using the initial condition improved by the three dimensional data assimilation system,MM5 had well simulated the land processes,intensity and moving track of Krovanh.Then,driven by 10-meter wind field output from MM5,the wave model WW3 reproduced the wave center well,but the intensity was 23%～33%lower than the observation by TOPEX/Poseidon(T/P).For typhoon landing,the intensity and spatial characteristics of storm surge were well simulated.Analyses of simulated winds andwaves showed that the distribution of typhoon waves were so closely related with the location and intensity of the eye that when the maximum wind speed region was in the right part of the typhoon,the center of significant wave height would be in the downwind direction of the typhoon.In the terms of time series,in the deep water the significant wave height had a good lag correlation with the maximum sea surface wind speed,with the biggest correlation coefficient being at 4 hours lag.While in the shallow water,although the wind speed changed little,the significant wave height increased very effectively as the water depth decreased,and the significant wave height decreased substantially when typhoons landed,which was consistent with the previous results.