OCO-2 flies in a Sun-synchronous, near-polar orbit with a group of Earth-orbiting platforms with synergistic science objectives that cross the equator around 13:30 hours Mean Local Time (MLT). Near-global coverage of the sunlit portion of Earth is provided over a 16-day (233-revolution) repeat cycle. OCO-2’s single instrument incorporates three high-resolution grating spectrometers that measure the near-infrared absorption of reflected sunlight by carbon dioxide and molecular oxygen.
The OCO-2 instrument acquires data in three different measurement modes.
- In nadir mode, the instrument views the ground directly below the spacecraft.
- In glint mode, the instrument tracks near the location where sunlight is directly reflected by Earth's surface, which enhances the instrument's ability to acquire highly accurate measurements, particularly over the ocean.
- In target mode, the instrument views a specified surface target continuously as the satellite passes overhead. Target mode provides the capability to collect a large number of measurements over sites where ground-based and airborne-instruments also measure atmospheric CO2.
ABSCO Tables Information
The ACOS/OCO-2/OCO-3 absorption coefficient (ABSCO) tables are “lookup tables” that supply cross-section values for absorbing gases in the Level 2 algorithm retrieval process. They record molecular absorption cross-sections over the range of relevant wavelengths, temperatures, and pressures in units of cm2/mol for the gases O2, H2O, and CO2.
Updated ABSCO tables are released together with each major build of the OCO-2 Level 2 algorithm and using the most recent tables is recommended.
Read the ABSCO User Guide for more information.