2 m气温集成订正方法及在冬奥延庆赛区的应用

An Integrated Correction Method for 2 m Temperature and Its Application to Yanqing Competition Zone of Olympic Winter Games

  • 摘要: 为提升北京冬(残)奥会气象服务保障能力,利用2018—2021年1月1日—3月28日欧洲中期天气预报中心(ECMWF)模式预报产品以及冬奥延庆赛区8个自动气象站的2 m气温实况,通过基于地形修正的模式偏差订正和支持向量机算法,构建赛区不同海拔高度站点72 h预报时效内逐3 h的2 m气温集成订正方法。2022年北京冬(残)奥会前夕及赛事期间应用评估表明:集成订正方法对延庆赛区2 m气温的预报准确率为0.856,平均绝对偏差为1.08℃,订正效果较单一订正方法更优,尤其针对海拔高度高出模式地形高度的站点订正性能更为突出,同时,对超阈值及关键过程的气温订正效果也表现较好。对于延庆赛区大多数站点而言,该方法订正的72 h预报时效内逐3 h的2 m气温平均绝对偏差总体上表现出一定的日变化特征,且0~24 h, 24~48 h, 48~72 h预报时效之间偏差变化相对平稳,但不同站点的日变化趋势存在差异。随着预报时效增加,该方法订正的2 m气温平均绝对偏差的变化趋势表现出海拔依赖性。

     

    Abstract: The snow events in Olympic Winter Games and Paralympic Winter Games are held outdoors in mountainous areas and especially weather sensitive. Unfavorable weather conditions can lead to delays or cancellations of competitions, and even affect the safety of athletes. With dramatic variability in the surface meteorological conditions at venues due to local topographic effects, the provision of timely and accurate high-quality weather prediction pose serious challenges to forecasters. Over the past decades, the accuracy of numerical weather prediction models is gradually improving, but there are still some systematic errors because of the inherent modeling deficiencies, especially in areas characterized by highly variable orography. Fortunately, the weather prediction accuracy is usually improved with the help of post-processing techniques.In order to improve the meteorological service capability of the snow events, an integrated correction method for 2 m temperature prediction, composed of the model bias correction based on terrain correction and support vector machine algorithm, is proposed at sites with different altitudes within 72 h at 3 h interval. European Center for Medium Range Weather Forecasts (ECMWF) model data from 1 January to 28 March during 2018-2021 and the observation of 2 m temperature at eight automatic weather stations in Yanqing competition zone are used. The performance of the integrated correction method is evaluated before and during Olympic Winter Games and Paralympic Winter Games. The results show that the accuracy of the correction method is 0.856 and the mean absolute error is 1.08℃ for 2 m temperature prediction in Yanqing competition zone. The integrated correction method is better than the single algorithm, and performs well in 2 m temperature prediction exceeding the threshold and key weather process forecasts. The performance of the integrated correction method is more outstanding especially for the sites higher than the terrain height of the model. For most of the sites, the mean absolute error of 2 m temperature predicted by the integrated correction method within 72 h at 3 h interval generally shows a certain diurnal variation, and the variation of mean absolute error within 0-24 h, 24-48 h and 48-72 h lead time is relatively stable, but the daily variation trend is different at different sites. With the increase of lead times, the mean absolute error of 2 m temperature predicted by the integrated correction method shows the altitude dependence. The relevant research results may be extended to other complex mountainous areas to improve the weather prediction accuracy.

     

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