西北中东部ECMWF-HR云量预报产品与FY-2G云量产品的对比

Comparison of cloud products of ECMWF-HR and FY-2G satellite in the central and eastern parts of Northwest China

为了了解ECMWF-HR模式云量预报产品在西北中东部地区的精度,利用2019年10月至2020年9月共计12个月的FY-2G卫星总云量反演产品,对西北地区中东部同时段的ECMWF-HR总云量预报产品进行对比分析,并选取3个典型区分析ECMWF-HR总云量预报偏差的日变化特征。结果表明,ECMWF-HR模式对西北地区中东部总云量的预报偏差白天较小,夜间偏差增大约10%~20%。总云量预报偏差具有明显的季节特征,夏半年ECMWF-HR模式云量预报整体偏多且偏差空间分布均匀;冬半年总云量预报有区域性特征,祁连山区西段明显偏低,甘肃和陕西南部明显偏多,其他大部地区的预报偏差低于夏半年。总体来说,ECMWF-HR模式总云量预报稳定可信,但在祁连山西段和甘肃与陕西南部2个明显异常区域需进行偏差订正。前者需要在模式预报基础上调高10%~30%,后者需要降低20%~30%;订正后的总云量预报与卫星反演结果较为接近,平均绝对偏差约4.5%,且与卫星反演结果具有相似的日变化特征。

The ECMWF-HR cloud forecast products are verified by using the total cloud cover inversion products of FY-2G satellite from October 2019 to September 2020 and the diurnal variation characteristics of ECMWF-HR total cloud cover products in the central and eastern parts of Northwest China are diagnosed in selected key areas to provide references for the application of cloud forecasting.The results show that the total cloud forecasted by the ECMWF-HR is relatively stable and has obvious diurnal characteristics in the study area.Forecast deviation is small in the daytime and at night it increases by 10%-20%.Meanwhile,there are obviously seasonal characteristics of cloud forecast product,and it has positive deviation in summer half year and the spatial distribution of the deviation is even.It shows regional distribution characteristics in winter half year with negative deviations in the western Qilian Mountains and posi⁃tive deviation in Gansu and the south part of Shanxi,and the deviation is lower in winter half year than in summer half year in other ar⁃eas.In general,the cloud forecast product of ECMWF-HR is relatively reliable in the study area,but in two regions,there are signifi⁃cant anomalies.Total cloud forecast needs to be increased by about 10%-30%in the western Qilian Mountains and decreased by about 20%-30%in Gansu and the south part of Shanxi on the base of ECMWF-HR product.The model correction results are relatively close to the satellite inversion results,with an average absolute deviation of 4.5%and similar diurnal variation characteristics.