Improvement of the Weather Research and Forecasting (WRF) model for solar resource assessments and forecasts under clear skies

A new capability for ingesting gridded aerosols data into the Weather Research and Forecasting (WRF) mesoscale model is being developed. The aim is to improve the shortwave downward solar radiation assessment and forecasting by equipping the model with a mechanism to ingest both high temporal and high spatial resolution aerosol data. This results in a reduction of the bias caused by any misrepresentation of the aerosol optical properties and their spatio-temporal variability. The main impact of this improvement is on the direct and diffuse components of solar radiation. We present here a preliminary study over the Continental United States using the Goddard Space Flight Center shortwave scheme, MODIS Level 3 aerosol optical depth data, and three ground stations of NOAA's SURFRAD radiation network. Results under cloudless conditions showed a relative improvement in the mean bias error of about 80% in the direct normal irradiance and up to about 70% in the diffuse irradiance, with respect to the model's run without aerosols, which is currently WRF's default operation mode.