Sources of variations in total column carbon dioxide
Observations of gradients in the total CO_2 column, (CO2), are expected to provide improved constraints on surface fluxes of CO_2. Here we use a general circulation model with a variety of prescribed carbon fluxes to investigate how variations in (CO_2) arise. On diurnal scales, variations are small and are forced by both local fluxes and advection. On seasonal scales, gradients are set by the north-south flux distribution. On synoptic scales, variations arise due to large-scale eddy-driven disturbances of the meridional gradient. In this case, because variations in (CO_2) are tied to synoptic activity, significant correlations exist between (CO_2) and dynamical tracers. We illustrate how such correlations can be used to describe the north-south gradients of (CO_2) and the underlying fluxes on continental scales. These simulations suggest a novel analysis framework for using column observations in carbon cycle science.
© 2011 Author(s). This work is distributed under the Creative Commons Attribution 3.0 License. Published by Copernicus Publications on behalf of the European Geosciences Union. Received: 11 November 2010. Published in Atmos. Chem. Phys. Discuss.: 16 December 2010. Revised: 15 March 2011. Accepted: 24 March 2011. Published: 18 April 2011. Article first published online: 21 Jun 2010. We thank Peter Rayer and Dietrich Feist for helpful reviews of this manuscript. Support for this work from the NASA Carbon Cycle Program grant NNX08AI86G is gratefully acknowledged. GKA acknowledges support from a NSF graduate fellowship and an AAUW dissertation fellowship. The simulations shown were performed on Caltech's Division of Geological and Planetary Sciences Dell cluster. CarbonTracker 2009 data were provided by NOAA ESRL, Boulder, Colorado, USA from the website at http://carbontracker.noaa.gov. Edited by: C. Gerbig.
Published - KeppelAleks2011p13841Atmos_Chem_Phys.pdf