基于莫宁-奥布霍夫相似理论的地面站点风速预报偏差订正

Correction of Wind Speed Forecast Deviations at Ground Stations Based on Monin-Obukhov Similarity Theory

地形不匹配会导致风速预报出现偏差。Monin-Obukhov(莫宁-奥布霍夫)相似理论表明近地面风速垂直变化符合对数率特征,基于相似理论并引入大气稳定度判定因子构建偏差订正方案,将地面风速预报由模式地形订正到实际地形。针对冬季和夏季华北区域内760多个站点进行15 d的批量试验发现,使用订正方案后冬季和夏季00时(世界时)起始预报的模式前12 h风速预报的平均偏差可以降低20%以上,24 h预报偏差降幅也可达到10%以上,不同预报时效内风速的均方根误差可降低5%~8%。说明使用偏差订正方案可以对模式地面风速预报产生明显正效果。

Due to the influence of the terrain difference,the model wind speed prediction may deviate from the actual observation.Monin-Obukhov similarity theory shows that the vertical change of wind speed near the ground conforms to the logarithmic rate characteristics.Based on this similarity theory,the deviation revision scheme is constructed to revise the wind speed forecast from the model terrain to the actual terrain,and the atmospheric stability determination factor is introduced to the scheme.After analyzing more than 760 stations in North China in summer and winter,we have found that the average deviation of wind speed forecast within 12 h can be reduced by more than 20%,the 24 h decline can also reach more than 10%,and the root mean square error of wind speed within different forecast periods can also be reduced by 5%-8%.This indicates that the revised scheme has a very obvious positive effect on the wind speed prediction of the model.