The GERB TOA reflected shortwave radiation (RSW) Obs4MIPs product has been generated from GERB level 2 HR RSW fluxes. There are five main stages. The first is to take the Edition 1 GERB HR SW flux data with the user corrections applied and generate an albedo using knowledge of the incoming SW flux for each location and time. The albedo is then area weighted to create a 1° by 1° spatial resolution albedo for every 15-minute time interval. These data are then averaged over time to produce an hourly averaged albedo product for each hour of each day. Each hour interval is defined as the time-centred mean at half-past the hour, e.g. 1030 UTC comprises the mean of albedos from 1000 UTC, 1015 UTC, 1030 UTC and 1045 UTC (or from those slots in this window that are available). An hourly average albedo is produced for a 1° by 1° grid cell if there is one or more observation from the four observation times available for that grid cell. The averaged albedos are converted back to RSW flux using the incoming solar flux at the midpoint of the hour and 1° cell. The fourth stage identifies days where there are no observations available for the hour and fills them with broadband RSW fluxes derived from the narrowband SEVIRI data, averaged to the daily hourly scale in the same way as the GERB data and corrected to the GERB observations at the monthly hourly 1° scale1. Finally, a monthly mean for each hourly time step is calculated encompassing the full data. The number of filled data points (days per monthly hourly average) contributing to each monthly hourly mean are used to estimate the uncertainties associated with the product. For more detailed information please see: Bantges, R., Russell, J., & Brindley, H. (2023). GERB-HR-ED01 rsut 1hrCM v1.1. Zenodo. https://doi.org/10.5281/zenodo.10034410.