基于小波分析的西北区智能网格气温客观预报方法的检验评估

Test and evaluation of Northwest Intelligent Grid Temperature Objective Prediction Method based on wavelet analysis

基于中国气象局(China Meterological Administration,CMA)高分辨率数值预报产品、欧洲中期数值预报中心(the European Center for Medium-range Weather Forecast,ECMWF)精细化数值预报产品和国家级地面观测站数据,采用小波分析方法及滑动训练、最优融合等技术对模式误差序列进行时频处理,实现了对模式系统误差和局地误差的订正,发展了西北区智能网格气温客观预报方法(northwest intelligent grid temperature objective prediction method,NWTM)。以2017年3月—2018年2月数据作为训练样本,对2018年3月—2019年1月西北区239个国家基本站进行检验。结果表明:1)NWTM对CMA和ECMWF两种模式产品的气温预报能力有显著的提升;随着预报时效增长,两种模式订正产品的误差增大。2)NWTM对ECMWF西北区最高气温的订正效果要明显优于CMA,但就最低气温而言,NWTM对CMA的订正效果更为显著。其中,就24 h最高气温而言,ECMWF在宁夏的订正效果最好,CMA在青海的订正效果最好;而对于24 h最低气温的预报,CMA在西北4省的订正效果相差不大,ECMWF在陕西的订正效果最好。3)空间误差检验表明:针对最高气温的预报,ECMWF订正产品的订正能力明显优于CMA,特别是在甘肃河西走廊和中东部、陕西北部和南部、宁夏中南部及青海大部。就最低气温的预报而言,ECMWF和CMA对甘肃河东和陕西南部的订正能力较好;ECMWF订正产品在宁夏中南部及青海南部的订正能力高于CMA,而CMA订正产品在陕西中部的订正能力更优。

Based on the high resolution numerical prediction products of China Meteorological Administration(CMA),the refined numerical prediction products of European Centre of Medium-range Weather Forecasts(ECMWF)and the data from national ground observation stations in China,the Northwest Intelligent Grid Temperature Objective Prediction Method(NWTM)has been developed by using wavelet analysis,sliding training,optimal fusion and other technologies,which can be used to deal with the time-frequency of the model error sequence and realize the correction of the model system error and local error.In order to test the forecast ability of the two model data,the data from March 2017 to February 2018 were used as training samples,the data of 239 national basic stations in Northwest China from March 2018 to January 2019 were tested.Results show that:(1)NETM can significantly improve the temperature forecast ability of CMA and ECMWF models.With the increase of forecast time,the errors of correction products of the two models increase.(2)Using the NWTM,the correction effect of ECMWF products on maximum temperature in Northwest China is obviously better than that of CMA,but the correction effect of CMA products on minimum temperature is more significant.Among them,for the 24 h maximum temperature,the correction effect of ECMWF in Ningxia is the best,and that of CMA in Qinghai is the best;for the forecast of 24 h minimum temperature,the correction effect of CMA in the four provinces of Northwest China is similar,and that of ECMWF in Shaanxi is the best.(3)The spatial error tests show that the correction ability of ECMWF correction products for the forecast of maximum temperature is obviously better than that of CMA,especially in the Hexi Corridor and the east-central region of Gansu,the north and south of Shaanxi,the south and central region of Ningxia,and most of Qinghai.In terms of the forecast of minimum temperature,CMA and ECMWF have better ability to correct the forecast of minimum temperature in Hedong region of Gansu and the south of Shaanxi.However,the correction ability of ECMWF correction products in the south-central region of Ningxia and the south of Qinghai is higher than that of CMA,while the correction ability of CMA correction products in the central region of Shaanxi is better.