Harmonizing the hourly solar radiation calculation from satellite-derived irradiance

Geostationary satellites provide highly accurate, gridded solar irradiance data on a global scale. However, because satellite-derived irradiance is based on instantaneous measurements, temporal aggregation techniques are needed for practical applications. In this study, we show that various temporal aggregation techniques for hourly solar radiation values are currently employed in both research publications and software tools for the widely adopted SARAH datasets. Our benchmarking reveals that these differing approaches lead to significant discrepancies, with mean absolute deviations up to three times. Notably, many studies neglect the influence of local satellite scan times, even though our results demonstrate that accounting for them significantly enhances aggregation accuracy. To address this gap, we introduce a simple, latitude-based heuristic that efficiently adjusts for scan time differences. Overall, our findings highlight the need to harmonize temporal aggregation methods, as they have a pronounced impact on the quality and consistency of solar radiation data and offer a practical technique to achieve this. • First study showing that currently different temporal aggregation techniques are. • Different temporal aggregation techniques lead to large deviations. • Proposed method considers correct satellite scan weighting and scan time delays. • Mean absolute deviations for hourly aggregation can be halved on average (BSRN stations).