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    基于机器学习的北京供暖季气温预报误差订正

    Bias correction of heating season temperature forecasts based on Machine Learning in Beijing

    • 摘要: 基于2019年7月1日至2024年3月15日水平分辨率为0.1°×0.1°的ECMWF模式预报数据和北京20个国家级气象站观测数据,分析北京历史供暖季ECMWF模式对2 m气温预报的误差特征,利用极限随机森林、决策树、梯度提升树、线性回归、Lasso回归算法对ECMWF模式的2 m气温预报误差进行订正。结果表明:ECMWF模式对北京城区2019—2023年供暖季2 m气温预报整体偏低,最大偏差出现在下午,平均偏差为-2.3 ℃,郊区2 m气温预报早晨偏低,下午偏高,最大正偏差和负偏差出现在07:00和16:00,分别为1.7 ℃和-2.2 ℃。利用机器学习方法订正后,2023年供暖季(2023年11月7日至2024年3月15日)北京城区和郊区的平均偏差和均方根误差均有明显降低,其中极限随机森林算法的订正效果最优,城区和郊区均方根误差分别改善了24.2%和35.4%;2023年供暖季北京城区9个站日平均气温预报偏差在±0.5、±1、±2 ℃内的准确率均显著提升,最大分别提升31%、44%和40%,极限随机森林和决策树算法表现最佳。

       

      Abstract: Based on the European Centre for meaium-Range Weather forecasts(ECMWF) model with a horizontal resolution of 0.1°×0.1° and the observation data from 20 national automatic weather sites in Beijing from July 1,2019 to March 15,2024,the characteristics of the model for 2 m temperature bias forecasted by ECMWF model during the historical heating season were analyzed.Extreme random forest,decision tree,gradient boosting tree,linear regression,and Lasso regression methods were used to correct the 2 m temperature forecasts from ECMWF model.The results show that the overall 2 m temperature forecast during the historical heating season in 2019-2023 in the urban area of Beijing by ECMWF is low,with the largest bias occurring in the afternoon and with the average bias of -2.3 ℃.While the 2 m temperature forecast in the suburban area is low in the morning and high in the afternoon,with the largest positive and negative bias occurring at 07:00 and 16:00,being 1.7 ℃ and -2.2 ℃,respectively.After the correction by machine learning method,the mean bias and root mean square error of urban and suburban sites in Beijing in the 2023 heating season (from November 7,2023 to March 15,2024) are significantly decreased,in which the correction effect of the extreme random forest is the best,and the improvement rates of root mean square error in the urban and suburban areas are 24.2% and 35.4%.After the correction by machine learning method,the accuracy of daily mean temperature forecast bias within ±0.5 ℃,±1.0 ℃ and ±2.0 ℃ at 9 sites in urban area of Beijing in the 2023 heating season is significantly improved,with the maximum improvement rates of 31%,44% and 40%,respectively,and the extreme random forest and decision tree have the best performance.

       

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