Evaluation of three radiation schemes of the WRF-Solar model for global surface solar radiation forecast: A case study in Egypt

Abstract

This study aims to assess the performance of three different radiation schemes in Weather Research and Forecasting (WRF) mesoscale model against ECMWF fifth generation (ERA5) Reanalysis data over Egypt. Dudhia, rrtmg, and Goddard schemes were used to simulate Global Horizontal Irradiance (SR) during 2017. Sixteen stations were selected to represent the different climate conditions in Egypt. The observed SR data is only available at five stations and used to evaluate the accuracy of ERA5 and WRF output. SR data at the other eleven stations were extracted from ERA5 to evaluate the corresponding values from WRF simulation. Coefficient of determination (R2), mean bias error (MBE), root mean square error (RMSE), monthly standard deviation (STDV) and mean absolute percentage error (MAPE%) are the implemented evaluation statistical parameters in the study. The results showed that ERA5 and WRF Dudhia scheme have reliable results as compared to the observations at the five stations. Also, the WRF Dudhia scheme simulates the SR at the other eleven stations better than rrtmg, and Goddard schemes as compared to ERA5 dataset. Where, the three WRF radiation schemes overestimate the SR along the eleven stations and underestimate at Alexandria station by −0.15 KWh/m2, which may due to the weather conditions over these sites. But the Dudhia scheme over the eleven stations has the lowest MBE (<0.34 KWh/m2), RMSE (<0.58 KWh/m2), and MAPE (<−2%), with R2 more than 0.985 at most stations.