ACOS GOSAT: Satellite-Derived Atmospheric CO2 Concentrations

ACOS GOSAT/TANSO-FTS Level 2 Full Physics Standard Product V9r provides column-averaged dry-air mole fractions of carbon dioxide (XCO2) from satellite soundings. The dataset is produced by NASA's OCO Project using spectral radiances from the GOSAT TANSO-FTS instrument and algorithm build version 7.3. Version 9r includes key algorithmic changes intended to reduce systematic biases and improve agreement with ground-based TCCON measurements.

Use Cases

• Monitoring global and regional carbon dioxide fluxes based on column-averaged XCO2 measurements.
• Validating and improving carbon cycle models using satellite-derived atmospheric concentration data.
• Assessing the impact of algorithm improvements on bias reduction by comparing to TCCON network data.
• Analyzing spatial and temporal trends in atmospheric CO2 from geolocated satellite soundings.

Strengths

• Represents a high-level, scientifically processed standard product from NASA's OCO Project.
• Algorithm version 9r includes specific improvements, such as O2-A band spectroscopy scaling, reported to reduce XCO2 bias by 4-5 ppm.
• Cross-platform presence on NASA-affiliated portals (Data.gov, NASA Earthdata) signals its importance and official status.

Limitations

• Critical metadata is missing or conflicting across sources: no row count, column names, or explicit license details are provided.
• The description is highly technical and repetitive across platforms, with sparse concrete details on data structure and access.
• Documentation includes a disclaimer that users must carefully review, indicating known issues or complexities.

Provenance

Source

National Aeronautics and Space Administration (NASA), OCO (Orbiting Carbon Observatory) Project, using data from the JAXA GOSAT TANSO-FTS instrument.

Collection Method

Derived from Level 1B calibrated radiances via the ACOS Level 2 full physics retrieval algorithm (build 7.3).

Freshness

Last updated: 2026-03-13 (as per Data.gov entries)

Geography

Global coverage from satellite soundings.