1,1,1,- 1DLR, Institute of Networked Energy Systems, Oldenburg, Germany (marion.schroedter-homscheidt@dlr.de)
- 2MINES Paris, PSL University, Sophia-Antipolis, France
As a part of the Copernicus Atmosphere Monitoring Service (CAMS), an hourly resolved 5 day forecast horizon irradiance forecast (IFS-COMPO) is provided regularly on the global scale. The particularity of this forecast is that It makes use of the CAMS forecast of the atmospheric composition, that is, aerosols, water vapor and ozone.
It is an overarching question, whether the IFS-COMPO provides radiation forecasts with an added value compare to ECMWF’s operational IFS-HRES (high resolution) forecast and whether it can be used as an operational product on itself. The IFS-COMPO forecast is operated on a low spatial resolution of 40 km. This is coarse compared to the 9 km spatial resolution of the operational IFS-HRES run. Moreover, the IFS-COMPO runs uses a modeled aerosol forecasts from CAMS while the operational ECMWF IFS-HRES uses only an aerosol climatology. It is not obvious which of the two model runs provides the better radiation forecast quality.
In this verification study an assessment on the years 2022and 2023 of the operational IFS-HRES forecast run in 9 km/1 hour spatio-temporal resolution and of the IFS-COMPO forecasts run in 40 km/1 hour spatio-temporal resolution is performed. The IFS-HRES run is used in its full spatial resolution but also spatially smoothed to a 40 km resolution which is directly comparable to the IFS-COMPO forecast resolution.
As the reference data for this verification study, high-quality ground observations from various climate zones around the world were obtained for the same year. A total of 63 stations belonging to 7 different measurement networks were retrieved for the study. The ground stations retained were then classified into 5 site classes: continental, desert, mountain, subpixel and polar. The statistical error metrics mean bias error (MBE), mean absolute error (MAE) and root mean square error (RMSE) were processed separately for each class in all sky conditions and in cloud free (also called ‘clear-sky’ in solar energy applications) conditions.
The main takeaways of the presentation are intended to be:
1) to present the CAMS IFS-COMPO irradiance forecast to the community
2) discuss recommendations for the solar energy community on how to use such a solar forecast based on an aerosol modeling approach.
How to cite: Schroedter-Homscheidt, M., Lezaca, J., Roy, A., and Saint-Drenan, Y.-M.: CAMS Solar Radiation day ahead forecasts: Site dependent evaluation of the IFS-COMPO forecast, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-552, https://doi.org/10.5194/ems2025-552, 2025.
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