Data Products

The OCO Ground Data System (GDS) will convert telemetry downloaded from the Observatory into data products that provide comprehensive mission results as well as material for further research and investigation. The GDS will provide the environment to generate two data products that will be available for distribution to both the scientific community and the general public. Both products will appear in the Hierarchical Data Format (HDF) v 5. The products will conform to the standards of the Earth Observing System Data and Information System (EOSDIS) Core System (ECS).

The OCO Level 1B product lists calibrated and geolocated spectral radiances. Each Level 1B product contains a unique record for every sounding that the OCO instrument acquires while viewing the Earth during a single spacecraft orbit. Each sounding consists of the three collocated spectra. Each of these spectra corresponds with one of the three spectrometer channels. If the instrument acquires data continuously over the entire daylight side of the Earth, the Level 1B Product contains approximately 37,000 soundings. The Level 1B product also includes error measures and indicators that assess the quality of each acquired spectrum. These indicators denote which spectra are suitable for subsequent processing.

The OCO Level 2 product provides several retrieved atmospheric and geophysical measures. The retrieved data in each product are based on the spectra that were acquired during the same OCO spacecraft orbit. The presence of clouds, thick aerosols and topographic inhomogeneities inhibits the retrieval process. A typical Level 2 Product is likely to list the output from about 3,700 retrievals. The retrieved data include vertical atmospheric profiles of temperature, CO₂ and water vapor as well as aerosol content. Each vertical profile appears as an array in the Level 2 Product. Each element in these arrays represents a location in the vertical profile Retrieved data also include scalar measures of albedo, surface pressure and the column averaged dry air CO₂ mole fraction (Xco₂). The Level 2 product contains error measures and indicators that assess the quality of the data output. These indicators specify whether the retrieved data sets are suitable for subsequent processing. Members of the OCO science team will generate Level 3 and Level 4 products at their home institutions. The Level 3 product will map Xco₂ to one part per million (ppm) accuracy over the Earth's surface in bins with dimensions of 1° in latitude and 1° in longitude. Each granule of the OCO Level 3 product will represent data from one 16 day orbit repeat cycle.. The Level 4 product will map the distribution of CO₂ sources and sinks over the Earth's surface. Plots of the Level 4 product will display fluxes in CO₂ abundance over the Earth's surface in regions with dimensions of 4° in latitude and 5° in longitude.

OCO Data Products
Level	Data Product	Data Rate	Latency
1B	Orbit granules of calibrated radiances	9.96 Gbytes/day	30 days
2	Orbit granules of geolocated Xco2	0.257 Gbytes/day	30 days
3	Global Xco2	N/A	N/A
4	Global CO2 sources and sinks	N/A	N/A