A Comparison Between the Atmospheric Component of HWRF System and WRF-HWRF Model Using Different Horizontal Resolutions in Hurricane Irma (2017) Simulation. Part I

Abstract A study of several configurations of numerical forecast models was conducted to evaluate their skill to forecast tropical cyclones track and intensity. For this, four configurations of the horizontal domain were selected with 27-9 and 18-6 km of resolution for HWRF (Hurricane Weather Research and Forecasting Model) and four configurations for the WRF (Weather Research and Forecasting Model), using the dynamic core NMM (Non-hydrostatic Mesoscale Model) with the vortex tracker option. Simulations corresponding to Hurricane Irma were done from 1st to 12th September 2017, initialized with GFS (Global Forecast System) forecast outputs. No notable differences were observed between the eight configurations, although the forecast of the intensity of Hurricane Irma was deficient, with an error in the forecast of the maximum wind speed above 50 km/h. The comparison of the outputs of each configuration with buoys and surface meteorological stations data showed that the behavior of the wind speed and atmospheric pressure variables has a similar tendency to the registered values in the stations, with errors lower than 3.8 m/s for wind speed and 3 hPa for atmospheric pressure. HWRF 18-6-m (referred to the model and the horizontal domain resolution) was the configuration that showed the best ability for tropical cyclones forecast, although it require large time to compute.摘要 本研究针对多款数值预报模式的不同配置展开实验，以评估其在热带气旋路径与强度预报中的预报技巧。为此，我们选取飓风天气研究与预报模式（Hurricane Weather Research and Forecasting Model，HWRF）的4套水平计算区域配置，分辨率分别为27-9 km与18-6 km；同时选取天气研究与预报模式（Weather Research and Forecasting Model，WRF）的4套配置，采用非静力中尺度模式（Non-hydrostatic Mesoscale Model，NMM）动力核心，并开启涡旋追踪功能。本研究以2017年9月1日至12日的飓风艾尔玛（Hurricane Irma）为模拟对象，初始场采用全球预报系统（Global Forecast System，GFS）的预报产品。实验结果显示，8套配置间未观测到显著性能差异，但飓风艾尔玛的强度预报效果欠佳，最大风速预报误差超过50 km/h。将各配置的模拟输出与浮标及地面气象站观测数据对比后发现，风速与大气压强变量的变化特征与站点实测值趋势一致，其中风速预报误差低于3.8 m/s，大气压强预报误差低于3 hPa。其中，HWRF 18-6-km（对应上述模式及水平计算域分辨率）的配置展现出最优的热带气旋预报性能，但其计算耗时较长。