"登台入闽"型台风个例10 m风场 特征分析及模拟研究

通过浮标资料和模拟试验,对比不同路径下台风的10 m风场的时空演变规律。结果表明,由于登陆台湾岛位置不同,三种路径的台风在台湾海峡内风场随时间变化差异较大,北路台风在海峡内风向转变最早,中路台风风速极值出现最早,南路风速被削减最明显。在中尺度数值模式(Weather Research Forecasting, WRF)模拟试验中,YSU边界层参数方案模拟效果最优,对于中路台风的模拟效果最好。模拟结果表明,北路台风在过岛过程中,大风圈从北部绕过海拔较高的地形,风速减弱不明显;中路和南路台风由于中低层环流难以过山,强风中心通过动力减压作用出现在背风坡,并范围逐渐增大,取代原中心。地形敏感性试验表明,受中央山脉影响,在靠近台湾岛时迎风面大气堆积风速增强,南路台风的风场在登陆福建前受地形阻挡削减最大,中心风速减小幅度为20 m·s^-1。

Characteristic analysis and simulation of 10 m wind field of typhoon cases which entering Fujian after landing on Taiwan

In this paper, attempted to compare the temporal and spatial evolutions of the 10 m wind field of three typical cases of typhoon with different paths based on buoy observations and simulation experiments. Due to the different locations of landing on Taiwan Island, significant variation of the wind fields of three typhoon cases are seen in the Taiwan Strait over time. Among the three typhoon cases, the wind direction of the typhoon on the north side changes the earliest in the Strait, and the extreme wind speed of typhoon in the middle appears earliest, whereas the wind speed of typhoon on the south side reduces most obviously. In the WRF simulation, the YSU boundary layer parameter scheme has the best performance, and the simulation of the typhoon in the middle is the closest to the reality. The simulation results show that the gale circle bypasses the terrain with higher altitude from the north, and the wind speed is not significantly weakened during the typhoon on the northside passing through the island. Typhoon in the middle and south are difficult to cross the mountain due to the low and middle level circulation. The strong wind center appears on the leeward slope through dynamic decompression, and the range increases gradually until replaces the original center. Through the terrain sensitivity test, the results show that the wind speed on the windward side increases when it approaches Taiwan Island due to terrain effect of the central mountain. In addition, the wind field of typhoon on south side can be significant obstructed by the terrain before it lands in Fujian, and the central wind speed decreased by at least 20 m·s^-1.