【摘要】 采用Grid Nudging(GN)和Spectral Nudging(SN)方法,用再分析资料ERA5和FNL驱动中尺度数值天气预报模式(WRF),探究不同再分析资料和Nudging方法对降水模拟效果的改进效果及机理.对2021年3月15日中国南方地区降水过程设计6组试验进行数值模拟,分析不同试验方案对降水及相关物理量的影响.结果表明, WRF模式能较好地模拟出本次降水事件,进行Nudging驱动后显著提升了降水分布、降水中心落区和降水量的模拟效果.与观测数据综合对比, GN的模拟效果优于SN,尤其是使用ERA5资料结合GN模拟效果最佳,能够准确地模拟出发生在安徽省南部的降水中心以及超过33 mm/d的降水强度.模式结果与两个观测站点记录的降水发生时间和降水强度变化较为一致. GN方法使模式有效提高了西南低空急流的强度,校正了风向,对水汽通量和水汽通量散度的刻画更符合实际情况.更多还原

【Abstract】 Grid Nudging(GN) and Spectral Nudging(SN) methods were adopted. The two most commonly used reanalysis data, ERA5 and FNL, were used to drive the weather research and forecasting(WRF)model mesoscale numerical weather prediction model, and the improved effects of different reanalysis data and Nudging methods on precipitation simulation and their causes were explored. Six sets of experiments were designed to numerically simulate a precipitation process in southern China on March 15,2021, and to analyze the influences of different experimental schemes on precipitation and related physical quantities. The results showed that the WRF model could simulate the precipitation event well, and the simulating effect after Nudging was significantly improved. A comprehensive comparison with the observation data showed that the simulation effect of GN was better than SN, especially that the combination of ERA5 data with GN had the best simulation effect, which could well simulate the spatial distribution of precipitation and the change in precipitation time. The characterization of the intensity, direction and water vapor flux divergence of the southwest low-level jet by the GN method was more consistent with the actual situation, thus further improing and enhancing the precipitation simulation performance.更多还原