OCO-2 data will start coming in about 45 days after launch. Why this time delay? It takes some time and maneuvering to get the satellite positioned exactly where we want it to be, in the right position in the A-train Constellation. After that, the mission operations team carefully turns on all the components and does checks to make sure everything is working correctly. Only after that, will the instrument go into work mode and start collecting data. On OCO-2, the data are stored on board and the information is sent down in bundles during orbit. Data and information (telemetry) are sent back to Earth and "collected" by the ground stations. Once the data are collected, they will still need to be processed. OCO-2 data will be processed at the jet Propulsion Lab and the data is ultimately distributed and stored at the Goddard Earth Science Data & Information Services Center (GES DISC).more
NASA Earth Satellite data products, including OCO-2, are processed at various levels ranging from Level 0 to Level 4. Unless a satellite is flying an actual camera, the data that comes back does not look like a picture or image. It must be created by the science team! Level 0 products are raw data at full instrument resolution. With each progressive level (1-4), the data are converted into more useful formats, such as a map and with more specific variables such as location and time.
The OCO-2 Science Data Operations System (SDOS) will convert automated readings downloaded from the Observatory into data products that provide comprehensive mission results as well as material for further research and investigation. The SDOS will provide the environment to generate two data products (i.e., L1 and L2) 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-2 Level 1B product will list calibrated and geo-located spectral radiances. Each Level 1B product will contain a unique record for every sounding that the OCO-2 instrument acquires while viewing the Earth during a single spacecraft orbit. Each sounding will consist of the three collocated spectra. Each of these spectra will correspond 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 will contain approximately 72,000 soundings per orbit. 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-2 Level 2 product will provide several retrieved atmospheric and geophysical measures. The retrieved data in each product will be based on the spectra that were acquired during the same OCO-2 spacecraft orbit. The presence of clouds, thick aerosols and topographic inhomogeneities inhibits the retrieval process. A typical Level 2 Product will likely list the output from about 9,400 retrievals. The retrieved data will include vertical atmospheric profiles of temperature, CO2 and water vapor as well as aerosol content. Each vertical profile will appear as an array in the Level 2 Product. Each element in these arrays will represent a location in the vertical profile. Retrieved data will also include scalar measures of albedo, surface pressure and the column averaged dry air CO2 mole fraction (Xco2). The Level 2 product will contain error measures and indicators that assess the quality of the data output. These indicators will specify whether the retrieved data sets are suitable for subsequent processing.
Members of the OCO-2 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-2 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-2 Data Products|
|Level||Data Product||Data Rate|
|1B||Orbit granules of calibrated radiances||19.95 Gbytes/day||30 days|
|2||Orbit granules of geolocated Xco2||0.54 Gbytes/day||30 days|
|4||Global CO2 sources and sinks||N/A||N/A|