WMO OSCAR | Details for Instrument GERB

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Instrument: GERB

Instrument details

Acronym	GERB
Full name	Geostationary Earth Radiation Budget
Purpose	Frequent observation of Earth radiation budget
Short description	Two broad-band channels, for solar reflected radiance and total reflected/emitted radiance [see detailed characteristics below]
Background	New development
Scanning Technique	Mechanical, spinning satellite, E-W continuous, S-N stepping
Resolution	42 km
Coverage / Cycle	Full disk every 5 min. Integration over three cycles (15 min) to comply with accuracy requirements
Mass	25 kg	Power	35 W	Data Rate	50.6 kbps

Providing Agency	UKSA
Instrument Maturity	Flown on operational programme
Utilization Period:	2004 to 2033
Last update:	2021-06-14

Detailed characteristics

Channel	Spectral interval	Noise Equivalent Radiance	Absolute accuracy	SNR
Short-wave	0.32 - 4.0 µm	0.8 W m^-2 sr^-1	2.4 W m^-2 sr^-1	1250
Total radiance	0.32 - 100 µm	0.15 W m^-2 sr^-1	0.4 W m^-2 sr^-1	400

Satellites this instrument is flying on

Note: a red tag indicates satellites no longer operational, a green tag indicates operational satellites, a blue tag indicates future satellites

Meteosat Second Generation (MSG) (EUMETSAT)
- Meteosat-8 (see instrument status) Aug 2002 - Jul 2016
- Meteosat-9 (see instrument status) Dec 2005 - Apr 2022
- Meteosat-10 (see instrument status) Jul 2012 - 2030
- Meteosat-11 (see instrument status) Jul 2015 - 2033
- Meteosat-8 (IODC) (see instrument status) Sep 2016 - Nov 2022

Instrument classification

Earth observation instrument
Passive optical radiometer or spectrometer
Broadband Earth radiation radiometer

WIGOS Subcomponents

Subcomponent 1
Absolutely calibrated broadband radiometers, and TSI and SSI radiometers
Broadband radiometer (for ERB)

Mission objectives

Primary mission objectives

Upward long-wave irradiance at TOA
Upward short-wave irradiance at TOA

Evaluation of Measurements

The following list indicates which measurements can typically be retrieved from this category of instrument. To see a full Gap Analysis by Variable, click on the respective variable.

Note: table can be sorted by clicking on the column headers
Note: * Primary mission objective.

Variable	Relevance for measuring this variable	Operational limitations	Explanation
Upward short-wave irradiance at TOA*	2 - very high	Information on BRDF needed.	SW and Total (SW+LW) broadband channels. Frequent sampling (GEO) enable capturing diurnal variations, particularly due to clouds. Also, changing solar incidence angle helps with irradiance computation
Upward long-wave irradiance at TOA*	2 - very high	No specific limitation.	LW radiance achieved by difference between Total and SW. Frequent sampling (GEO) enable capturing diurnal variations due to clouds.and water vapour rapid evolution