The GERB TOA outgoing longwave radiation (OLR) Obs4MIPs product has been generated from GERB level 2 HR OLR fluxes. There are four main stages. The first ingests the Edition 1 GERB HR OLR data and generates an area weighted flux product at 1° by 1° spatial resolution for every 15-minute time interval. In the second stage these data are averaged over time to produce an hourly averaged product. Each hour interval is defined as the time-centred mean at half-past the hour, e.g. 1030 UTC, comprises the mean of data from 1000 UTC, 1015 UTC, 1030 UTC and 1045 UTC (or from those slots in this window that are available). An hourly average is produced for a 1° by 1° grid cell if there is at least one of the four observation times available for that grid cell. If no available data are available for a particular hour of a day, then the third stage is implemented, and these hours are filled using broadband fluxes derived from the narrowband SEVIRI data corrected to the GERB observations at the monthly hourly 1° scale1. The final processing stage averages the hourly mean fluxes over the days in the month to produce a one degree monthly hourly mean product. The number of filled data points (days per monthly hourly mean) contributing to each monthly 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 rlut 1hrCM v1.1. Zenodo. https://doi.org/10.5281/zenodo.10034430.