Leveraging the satellite-based climate data record CLARA-A3 to understand trends and climate regimes relevant for solar energy applications over Europe

Abstract. Efficient transitioning to renewable energy requires fundamental understanding of the past and future climate change. This is particularly true in the case of solar energy since the surface incoming solar radiation (SIS) is regulated heavily by atmospheric essential climate variables (ECVs) such as aerosols and clouds, and by their long-term trends. Given the complexity of the interactions and feedbacks in the Earth system, even small changes in ECVs could have large direct and indirect effects on SIS. The net efficacy of the designed solar energy systems therefore depends on how well we account for the role of ECVs in modulating SIS at decadal scales. In this study, by leveraging the satellite-based climate data record CLARA-A3, we investigate the recent trends in SIS and cloud properties over Europe during the 1982–2020 period. Further, we derive emerging climate regimes that are relevant for solar energy applications. Results show a large-scale increase in SIS in spring and early summer over Europe, particularly noticeable in April and June. The corresponding trends in cloud fraction and cloud optical thickness, and their correlation with SIS suggest an increasingly important role of clouds in defining the favorable and unfavorable climate regimes for solar energy applications. We note also a strong spatio-temporal variability in trends and correlations. The results provide valuable metrics for the evaluation of climate models that have a dynamically integrated solar energy component.