Adapting WRF for Solar Forecasts Clear sky conditions - more often, less error, most easily fixed Cloudy conditions – less frequent, more error All errors worse for DNI than GHI

Clear sky conditions

May clear sky average error by time of day Forecast-Observed Sunrise NoonSunset

June average error by time of day clear sky, no smoke Sunrise NoonSunset

Cloudy Conditions Significantly more variability Can break up clouds into different cases with different physics Dust algorithm nearly eliminates bias in July, suggesting total cloud mass is proper Error mostly related to time and location of convective clouds Slight underprediction of winter clouds? We will get more data on this later this year.

MonthBias(total error)Average error: uncorrected May corrected May uncorrected June corrected June uncorrected July corrected July