Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado, USA
Received: 17 Apr 2008 – Published in Atmos. Chem. Phys. Discuss.: 08 Jul 2008 – Published: 12 May 2009
Abstract. The Orbiting Carbon Observatory (OCO) and the Greenhouse gases Observing SATellite (GOSAT) will make global observations of the total column dry-air mole fraction of atmospheric CO2 (XCO2) starting in 2008. Although satellites have global coverage, XCO2 retrievals will be made only a few times each month over a given location and will only be sampled in clear conditions. Modelers will use XCO2 in atmospheric inversions to estimate carbon sources and sinks; however, if satellite measurements are used to represent temporal averages, modelers may incur temporal sampling errors. We investigate these errors using a global transport model. Temporal sampling errors vary with time and location, exhibit spatially coherent patterns, and are greatest over land and during summer. These errors often exceed 1 ppm and must be addressed in a data assimilation system by correct simulation of synoptic CO2 variations associated with cloud systems.
Citation: Corbin, K. D., Denning, A. S., and Parazoo, N. C.: Assessing temporal clear-sky errors in assimilation of satellite CO2 retrievals using a global transport model, Atmos. Chem. Phys., 9, 3043-3048, doi:10.5194/acp-9-3043-2009, 2009.