基于WRF和一维雾模式的能见度集合预报的个例研究

Ensemble forecast of visibility based on WRF and one-dimensional fog model：A case study

摘要:

利用WRF（weather research and forecasting）中尺度模式为一维辐射雾模式PAFOG提供扰动场，构建了一个有30个成员的辐射雾集合预报系统。对2007年12月13—14日南京地区一次典型辐射雾过程进行了预报效果分析，结果表明：该方法在地面能见度预报及雾层垂直结构预报上均好于实际探空作为初始场的单一预报结果；模式启动时刻对预报结果有较大影响，由于辐射雾多发生在夜间，且模式需要一定时间达到稳定，本方法中一维模式在14：00启动预报效果最好，集合预报成员与实测值的标准差平均值为0.516 km，集合平均值的平均预报绝对误差为0.287 km。

关键词:辐射雾;数值模拟;集合预报;南京

Abstract:

An ensemble fog forecast system was designed based on WRF and a high resolution numerical 1-D model called PAFOG,whose initial perturbation conditions were obtained from the simulation of WRF.Comparison between prediction and observation was made during a typical radiation fog event that occurred in Nanjing during 13—14 December 2007.The results show the ensemble forecast system is better than single forecast.By using this method,the predictions for both visibility on surface and vertical structure of fog are better than those utilizing the model only initialized by radiosonde observation.The initial time of simulation played an important role in prediction accuracy.Because most radiation fog occurs at night and it takes some time for the model to stabilize,the best time to start the one-dimensional model is 14:00.The standard deviation between ensemble member and observation is 0.516 and the absolute error of ensemble average is 0.287 km.

Key words:radiation fog;numerical simulation;ensemble forecast;Nanjing