Assessing temporal clear-sky errors in assimilation of satellite CO2 retrievals using a global transport model K. D. Corbin, A. S. Denning, and N. C. Parazoo Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado, USA
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.