Geostationary Earth Radiation Budget

The Geostationary Earth Radiation Budget (GERB) is a two-channel broadband radiometer designed to measure top-of-atmosphere reflected solar and thermal radiation from geostationary orbit.^[1][2] Its shortwave channel covers approximately 0.32 to 4.0 micrometres, capturing reflected solar radiation; its total broadband channel spans from approximately 0.32 micrometres into the far infrared, measuring the combined solar and thermal emission.^[3]

GERB operates at coarser spatial sampling than its co-flying companion SEVIRI, with pixel dimensions of approximately 44.6 km (north-south) by 39.3 km (east-west) at nadir.^[3] Each full Earth disc scene is acquired in approximately 2.5 minutes, and observations are synchronised with SEVIRI's 15-minute imaging cycle.^[3] The instrument mass is approximately 25 kg with an average power draw of approximately 35 W.^[3]

GERB instruments have been carried on MSG-1 (Meteosat-8, hosting GERB-2), MSG-2 (Meteosat-9, hosting GERB-1), and MSG-3 (Meteosat-10, hosting GERB-3).^[1][3] GERB-3 on MSG-3 experienced an anomaly in 2013 that placed it in safe mode; its current operational status is uncertain.^[2] GERB-4 was included on MSG-4 (Meteosat-11) but had not been activated as of the instrument's last documented status.^[4] GERB supports broadband radiometry for Earth radiation budget science and climate monitoring.