台风“玛莉亚”风场WRF模拟及最大风速半径的非对称特性

WRF-BASED SIMULATION OF WIND FIELD AND ASYMMETRY FEATURE OF RADIUS TO MAXIMUM WINDS DURING TYPHOON MARIA

台风具有极强的破坏性,准确重现台风风场是保证台风影响区结构安全的关键。最大风速半径作为台风场计算的关键参数之一,研究其分布特性十分重要。以对我国产生严重影响的1808号超强台风“玛莉亚”为例,借助中尺度数值预报模式WRF,开展了该台风期间风场的精细化模拟。为保证模拟风场的准确性,共设置了7种参数化方案组合进行对比。利用最优的模拟结果对风场的分布特点进行研究,分析了地形变化对台风结构的影响。搜索出台风各方向的最大风速半径,并引入工程中常用的Holland气压模型及参数风场中的梯度风速来说明最大风速半径非对称性的影响。研究表明:不同微物理方案对台风“玛莉亚”路径模拟的影响很小,但对海面最低气压有一定影响,采用Lin微物理方案、RRTM长波辐射方案、Dudhia短波辐射方案,模拟效果较好;台风“玛莉亚”期间风场受下垫面地形变化影响较大,当地形由海面转为陆地时,风速逐渐下降;最大风速半径具有较强非对称性,忽略其非对称性会影响径向气压和风速的分布。

Typhoons are extremely destructive,and the accurate reproduction of typhoon wind fields is the key to ensure the structural safety in typhoon-affected areas.The maximum wind speed radius is one of the key parameters in typhoon field calculation,and it is very important to study its distribution.Taking the NO.1808 super typhoon Maria as an example,the wind field was simulated by the mesoscale numerical prediction model WRF.A total of 7 parameterization scheme combinations were set for comparison to ensure the accuracy of the simulated wind field.The wind field is studied using the optimal simulation results,and the influence of topographic changes on typhoon structure is analyzed.The radius to maximum wind speeds in each direction of the typhoon is searched.The Holland pressure model and gradient component of the parametric wind field model are introduced to illustrate the effect of the asymmetry of radius to maximum wind speeds.The research results show that:adopting different microphysics schemes has little influence on Maria’s track simulation but changes the minimum sea-level pressure,and using Lin microphysics scheme,RRTM long-wave radiation scheme,and Dudhia short-wave radiation scheme can have better simulation results;the typhoon wind field was greatly affected by the change of underlying surface topography during Maria,and the wind speed gradually decreased when the topography changed from sea to land;the radius to maximum wind speeds shows a strong asymmetry and ignoring the asymmetry will affect the distribution of radial pressure and wind speed.