基于3种能见度方案山东地区雾天气预报试验研究

摘要

基于中尺度天气研究与预报(Weather Research and Forecast,WRF)快速更新循环(Rapid Update Cycle,RUC)模式系统,选取SW(Stoelinga and Warner)方案、RUC方案与FSL(Forecast Systems Laboratory)方案3 种能见度方案,对2015 年10月至2016年3月山东地区的25次雾天气个例进行预报试验,包括能见度的定量化预报和雾天气的有、无诊断预报,利用常规气象观测资料对预报结果进行检验评估,并分析不同能见度方案对雾天气预报效果不佳的原因,对RUC方案进行订正.结果表明:SW方案模拟的能见度平均绝对误差为9—12 km,RUC方案和FSL方案模拟的能见度平均绝对误差均为2—4 km.对于山东地区大部分雾天气预报试验,SW方案和FSL方案雾天气预报的确报率高于误报率,均对雾天气具有一定的预报能力;RUC方案雾天气预报的确报率和误报率均为0,对雾天气没有预报能力.综合山东地区能见度与雾天气的预报效果可知,FSL方案更适合作为WRF-RUC模式业务中雾天气的预报产品.模拟能见度对相对湿度的预报误差过于敏感、未考虑空气中的污染物对能见度的影响及计算公式未进行本地化订正是能见度方案对雾天气预报效果不佳的主要原因,订正后的RUC方案模拟的能见度平均绝对误差较原始方案减小,且提高了雾天气的预报效果.%Based on Weather Research and Forecast(WRF)-Rapid Update Cycle(RUC)model system,three op-erational visibility schemes,including Stoelinga and Warner(SW)scheme,RUC scheme and Forecast Systems La-boratory(FSL)scheme,were used to make a forecast experiment for 25 fog events from October of 2015 to March of 2016 in Shandong province.The experiment included quantitative forecast of visibility and diagnostic forecast on weather fog occurs.The forecasting result is evaluated using routine meteorological observations.The causes of bad forecast on fog weather by different schemes were analyzed and then the RUC scheme was im-proved.The results indicated that the mean absolute error of visibility computed by the SW scheme ranges between 9 km and 12 km,while that computed by RUC scheme and FSL scheme varies within 2-4 km.For most of the fog events over Shandong province in the forecast experiment,the hit rate is larger than the false alarm rate based on the SW scheme and the FSL scheme,which means that the two schemes have a certain capability to forecast fog e-vents.However,the hit rate and false alarm rate of fog prediction by the RUC scheme are both zero,indicating that this scheme has no ability to forecast fog.Combining the evaluating results of visibility and fog,the FSL scheme is more suitable to produce the operational product of fog in the WRF-RUC model.The major causes of bad predic-tive results include that the simulated visibility is very sensitive to the error of relative humidity,the influence of air pollutant on visibility is not considered,and lack of appropriate localized revision impact on the forecast effect of visibility scheme on fog.After improving the RUC scheme,the mean absolute error of the visibility deceases and the forecasting performance of fog is improved.