Preliminary Results from the NASA Orbiting Carbon Observatory–2 (OCO-2)

Abstract:

The NASA Orbiting Carbon Observatory – 2 (OCO-2) was successfully launched from Vandenberg Air Force Base at 9:56:44 UTC on July 2, 2014. After a series of spacecraft checkout activities and orbit raising maneuvers, OCO-2 was inserted at the front of the 705-km Afternoon constellation (A-Train) on August 3^rd. This presentation will summarize the science objectives, review the measurement approach, and introduce some preliminary data from the first few months of operation.

OCO-2 was designed to return estimates of the column-averaged atmospheric carbon dioxide (CO₂) dry air mole fraction (X_CO2) with the precision, resolution, and coverage needed to quantify CO₂ surface fluxes on regional scales. To meet these goals, it carries and points a 3-channel grating spectrometer that collects high resolution, co-bore-sighted spectra of reflected sunlight in the 765 nm O₂ A-band and in the CO₂ bands centered near 1610 and 2060 nm. Each channel records 24 spectra per second along a narrow (< 0.8-degree) track, returning about one million soundings each day. At least 10% of these soundings are expected to be sufficiently cloud free to yield full-column estimates of X_CO2with single-sounding accuracies of 0.25 % on regional scales at monthly intervals.

The instrument is calibrated using on-board sources and targets, the Moon, well-characterized surface sites (Pollock et al. this session), and comparisons with nearly-coincident observations from the Japanese Greenhouse gases Observing SATellite (GOSAT; Kuze et al. this session). Cloudy soundings are identified and screened out (Taylor et al. this session) and the remaining soundings are analyzed to yield spatially-resolved estimates of X_CO2 and other geophysical products (c.f. Frankenberg et al. this session). OCO-2 X_CO2 estimates are then validated against those from the Total Carbon Column Observing Network (TCCON) to assess their accuracy and precision (Wennberg et al. this session). Preliminary products from each step of this process will be introduced here.

Before the end of 2014, the OCO-2 project will start delivering calibrated radiance spectra to the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) for distribution to the science community. Estimates of X_CO2 will start being delivered to the GES DISC during the first quarter of 2015.