摘要:利用中尺度数值模式WRF v3.8中的YSU、MYJ、QNSE、ACM2、UW、GBM、Boulac七种不同边界层参数化方案，采用高分辨率（1.33 km）数值试验的方法研究了不同边界层方案对模拟台风“莫兰蒂”（1614）登陆减弱阶段的移动路径、强度、结构、降水量、近地层有关物理量场分布等方面的影响，结果表明：（1）“莫兰蒂”台风登陆减弱阶段，不同边界层方案对台风路径、强度、降水量模拟影响显著，24 h内模拟台风路径、最低气压、最大风速及24 h累积降水量极值的最大差异分别达80 km、11 hPa、27 m s?1及241 mm；（2）Boulac方案模拟台风路径与实况最为接近，GBM、YSU和MYJ方案分别次之，ACM2和UW方案再次之，而QNSE方案最差；UW和QNSE方案模拟的最低气压以及MYJ和QNSE方案模拟的最大风速与观测最为接近；不同边界层方案均模拟出台风登陆阶段最低气压逐渐升高以及其升高速率在台风登陆后大于登陆前的特征，这与实况一致，但台风登陆前各方案模拟最低气压升高速度均大于实况，而台风登陆后却又不及实况；（3）Boulac方案模拟的24 h降水分布、强降水落区、结构、强度和各量级降水TS评分均最优，MYJ方案次之；而QNSE、UW和ACM2方案雨带向西北方向推进过快，各量级降水TS评分均较差；（4）综合台风路径、强度和降水模拟，Boulac和MYJ方案相对最优，其中Boulac方案在台风路径和降水模拟上更优，而MYJ方案在台风强度模拟上更优；YSU和GBM方案次之，而QNSE、UW和ACM2方案相对较差；（5）不同边界层方案计算的近地层潜热通量、感热通量显著不同，进而影响台风路径、强度、降水量模拟存在显著差异。比较而言，QNSE方案潜热通量相对异常偏高，MYJ和Boulac方案量值适中，其余方案相对偏低；QNSE方案感热通量相对略偏高，MYJ方案适中，其他方案则相对显著偏低；（6）不同边界层方案模拟降水区边界层热、动力结构显著不同，其中Boulac方案具有较明显优势，尤其是对日间边界层结构的模拟。
关键词:台风/
边界层参数化方案/
数值模拟/
热通量
Abstract:To study the effects of different boundary layer schemes on the simulation of landing attenuation stage of typhoon Meranti (1614), a series of high-resolution (1.33 km) numerical tests were carried out using seven boundary layer parameterization schemes in the mesoscale numerical model WRF v3.8, namely, YSU, MYJ, QNSE, ACM2, UW, GBM, and Boulac, in terms of movement track, intensity, structure, rainfall, and near-surface physical variables. The results indicate the following. First, boundary layer schemes significantly influenced the simulation of typhoon Meranti’s track, intensity, and rainfall during its landing attenuation stage, and the maximum differences in the 24-h simulated typhoon track, lowest atmospheric pressure, maximum wind velocity, and 24-h cumulative rainfall extremum were 80 km, 11 hPa, 27 m s?1, and 241 mm, respectively. Second, simulation results of the Boulac scheme showed a typhoon track that is closest to real-time results, followed by GBM, YSU, and MYJ schemes, and then by ACM2 and UW schemes, whereas the QNSE scheme displayed the worst simulation. Meanwhile, the UW and QNSE schemes simulated the lowest atmospheric pressure values, and MYJ and QNSE schemes simulated the maximum wind velocity values that are closest to actual observations. All boundary layer schemes simulated the features of the typhoon. For example, the lowest atmospheric pressure increased gradually during the landing stage, and the rate of such increase after landing was greater than that before landing, which agreed with real-time results. However, the increasing rate of the lowest atmospheric pressure before the typhoon landing that was simulated by each scheme is greater than the real-time result, whereas such increasing rate after typhoon landing is less than the real-time result. Third, the Boulac scheme best simulated the 24-h precipitation distribution, heavy precipitation area, structure, intensity, and TS score of precipitation at each level, whereas the MYJ scheme was the second best. As simulated by QNSE, UW, and ACM2 schemes, the rain belt advanced so quickly northwestward that the TS scores of precipitation at various levels were poor. Fourth, in the overall simulation of track, intensity, and precipitation of the typhoon, Boulac and MYJ schemes showed optimal results, in which the Boulac scheme was superior in simulating the typhoon track and precipitation and the MYJ scheme was superior in simulating typhoon intensity. The YSU and GBM schemes had the second best simulation results, whereas QNSE, UW, and ACM2 schemes had worse simulation performance. Moreover, the boundary layer schemes significantly differed in calculating the latent heat flux and sensible heat flux of near-surface layer, thereby affecting the simulation of typhoon track, intensity, and rainfall, leading to significantly different simulation results. The QNSE scheme resulted in an abnormally high latent heat flux, the MYJ and Boulac schemes resulted in the most modest values, and other schemes resulted in slightly smaller values. On the other hand, the QNSE scheme had a slightly higher sensible heat flux, the MYJ scheme showed the most modest one, and other schemes resulted in significantly smaller values. Finally, the boundary layer schemes significantly differed in the simulated thermal and dynamical structure of boundary layer, and Boulac scheme had the obvious advantages, particularly for the structure of boundary layer in daytime.
Key words:Typhoon/
Boundary layer parameterization schemes/
Numerical simulation/
Heat flux
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