中国大陆地区ERA5下行短波辐射数据适用性评估与对比

ERA5地表下行太阳短波辐射数据是欧洲中期天气预报中心（ECMWF）最新的,具有高时空分辨率的再分析产品,该短波辐射产品可作为陆面模式大气强迫数据之一,并在区域气候评估、农业以及太阳能资源等方面具有重要应用。本文利用中国区域2011—2018年经过质控的91个国家级地面辐射站点观测数据,对其在中国大陆地区的适用性进行多时空尺度的评估,并与ERA-Interim、CFSR、MERRA2共3套全球大气再分析产品和1套CERES卫星反演SYN1deg的产品进行了比较。结果表明：① 在月均值尺度上,与其他再分析产品比较,ERA5产品与站点数据的Corr最高（0.939）,RMSE最小（28.309 W/m²）,Bias（15.4 W/m²）略大于ERA-Interim产品（13.2 W/m²）;CERES卫星反演产品与站点数据的Corr为0.955,RMSE为20.042 W/m²,Bias为5.3 W/m²;② 5套产品的辐射值均高于地面观测数据,存在高估现象,总体上,ERA5产品在中国大陆地区的整体精度高于其他再分析产品,但与CERES卫星反演产品还存在一定差距,日均值比较结论亦具有相似规律。③ 分区评估结果表明在再分析产品中,ERA5产品在4个区域与观测数据都有更好的一致性,但5套产品均在南部区域表现不佳。并且与东北和北部区域相比,ERA5产品和CERES卫星反演产品在西部区域和观测数据相比的RMSE和Bias也相对偏大。

Evaluation and Comparison of Downward Solar Radiation from New Generation Atmospheric Reanalysis ERA5 across Mainland China

The European Centre for Medium-Range Weather Forecasts (ECMWF) has developed ERA5, a global atmospheric reanalysis product with high spatiotemporal resolution. The Shortwave Downward Radiation (SWDN) of ERA5 is an important atmospheric forcing dataset which has important applications in regional climate assessment, agriculture, and solar energy resource utilization. In this study, the observed SWDN dataset after quality control was collected from 91 official radiation monitoring stations across mainland China in 2011-2018 and was applied to evaluate the SWDN in ERA5 on different spatial and temporal scales, together with other three reference SWDN datasets from global atmospheric reanalysis products (i.e., ERA-Interim, CFSR, and MERRA2) and the CERES satellite inversion product (SYN1deg). Results show that: ① On the monthly mean scale, the ERA5 product had the highest correlation coefficient (Corr) with the station observation data (0.939) and the lowest Root Mean Square Error (RMSE) (28.309 W/m²), compared with other reanalysis products. The average bias of ERA5 (15.4 W/m²) was slightly higher than that of the ERA-Interim product (13.2W/m²). The Corr between CERES satellite inversion product and observation data was 0.955, the RMSE was 20.042W/m², and the Bias was 5.3W/m²; ② The radiation values of all these five SWDN products were overestimated against the observation data. In general, the overall accuracy of the ERA5 product in mainland China was higher than the other reanalysis products, but was lower than the CERES satellite inversion product. The comparison of daily mean values between products also showed similar results; ③ Regional evaluation results show that the SWDN in ERA5 had a good consistency with observation data in four regions across mainland China. All five SWDN products performed poorly in the southern region. Compared to the northeastern and northern regions, the RSME and the bias of the ERA5 product and the CERES satellite inversion product relative to observations were larger in the western region.