CEOS EO HANDBOOK – INSTRUMENT SUMMARY - Scanning Spectrometer (GeoCarb) -
Full Name Scanning Spectrometer (GeoCarb) Status No longer considered
Instrument Agencies NASA Maturity
Instrument Type Atmospheric chemistry Geometry TBD
Instrument Technology High-resolution nadir-scanning SW spectrometer Sampling TBD
Data Access Open Access Data Format TBD
Measurements and Applications GeoCarb Mission employs a 4-channel slit imaging spectrometer that measures reflected IR sunlight at wavelengths 1.61µm and 2.06µm for XCO2, and 2.32µm for XCH4 and XCO. The fourth channel, 0.76µm, measures O2 column concentration and SIF, and it also provides valuable information on aerosol and cloud contamination. The North/South (N/S) extent of the scan is fixed at a 4.4° field of view, which maps to 25° latitude or 2800 km at the Sub-Satellite Point (SSP). There are 1016 N/S samples with 4.1 km spatial resolution, spaced 2.7 km apart on center. The measurements are acquired in an East to West (E/W), 0.3825s step, and 4.08s stare (integration) mode, with 3 km sampling EW steps and 5.4 km resolution at SSP.
Resolution Summary 3 km by 4.1 km at nadir
Swath Summary From 55 degrees N to 55 degrees S
[Max Swath: 2500 km]
Accuracy Summary 0.2% or 0.8ppm (whichever is greater) for XCO2 as measured against time integrated TCCON observations at multiple sites, 0.6% or 10.0 ppb (whichever is greater) for XCH4 as measured against time integrated TCCON observations at multiple sites, 10% or 10.0 ppb (whichever is greater) for XCO as measured against time integrated TCCON observations at multiple sites. Retrieve estimates of solar induced fluorescence (SIF) from spectral measurements of the Fraunhofer lines near 758 nm and 770 nm with a NESR that is better than 0.5 mW/(m2 sr nm).
Waveband Summary 0.76 µm, 1.61 µm, 2.06 µm, 2.32µm
SWIR (~1.3 µm - ~3.0 µm)
Instrument Measurements
Measurements Overview
CategoryParameter
Trace gases (excluding ozone)CH4 Mole Fraction
CO2 Mole Fraction
CO Mole Fraction
Thematic Links Global Climate Observing System Essential Climate Variables (GCOS ECVs)
ECVDescriptionProduct(s)ECV Inventory 3.0 Record(s)
Carbon Dioxide, Methane and other Greenhouse gases click here click here search ECV Inventory records
Precursors (supporting the Aerosol and Ozone ECVs) click here click here search ECV Inventory records
Instrument Missions
GeoCarb - Geostationary Carbon Cycle Observatory (2025 - 2028)