Measuring the Skill of Numerical Weather Prediction Modelsat Forecasting Solar Ramp Events

A Ramp Tool and Metric (RT&M) was developed during the first Wind Forecast Improvement Project (WFIP) for measuring the skill of models at forecasting wind ramp events. This tool identifies ramp events in the time series of wind power, matches in time each forecast ramp event with the most appropriate observed ramp event, computes the skill score of the forecast model incorporating both phase (timing) and amplitude errors. An important feature of the RT&M is that it computes the ramp skill integrating over a range of changes of power (Δp) and duration (Δt) of ramp events.

The same basic concepts used in the RT&M for wind ramps are now adapted to characterize solar ramps and to measure the skill of models at forecasting them. Observations of Direct Normal Irradiance (DNI) collected at seventeen sites from the U.S. Department of Energy’s ARM Southern Great Plains (SGP) facility are used in the RT&M_solar and compared to forecasts from the NOAA High Resolution Rapid Refresh (HRRR) model. Preliminary results will show the basics of the RT&M_solar and how it can be used to evaluate models.