Extensive validation of CM SAF surface radiation products over Europe

Area of Science:

• Earth and Atmospheric Sciences
• Climate Science
• Remote Sensing

Background:

• Satellite-based radiation products are crucial for climate monitoring.
• Validation against ground-based measurements is essential for assessing data quality.
• Previous studies highlight variability in satellite data accuracy across different regions.

Purpose of the Study:

• To validate three satellite-based solar radiation datasets (CM SAF's SARAH-JRC, CLARA-A2, and an operational product) against an extensive pyranometer network in Europe.
• To assess the quality of daily means from CM SAF datasets and identify factors affecting validation.
• To compare satellite data accuracy with ERA-Interim reanalysis data.

Main Methods:

• Utilized data from 313 pyranometers across Europe spanning 2005-2015.
• Compared satellite-derived solar radiation (including SARAH-JRC, CLARA-A2, and an operational product) with ground measurements.
• Analyzed the impact of pyranometer quality (e.g., Second Class, silicon-based photodiodes) and geographical factors on validation metrics like Mean Absolute Deviation (MAD).

Main Results:

• SARAH-JRC demonstrated the highest accuracy and consistency for climate monitoring applications.
• Validation accuracy was best in Central Europe (MAD 8-13 W/m²), decreasing in high-latitudes, snow-covered areas, mountains, and coastal regions.
• Pyranometer quality was the most critical uncertainty source; lower-quality instruments increased errors and bias.
• ERA-Interim reanalysis showed the largest deviations from surface measurements.

Conclusions:

• SARAH-JRC is a reliable dataset for climate monitoring applications due to its demonstrated accuracy over a dense network.
• The quality of ground-based pyranometers is paramount for accurate satellite data validation.
• Geographical factors significantly influence satellite radiation product accuracy, necessitating careful consideration during validation.