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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 109, D02301, doi:10.1029/2003JD003968, 2004

Differences between surface and column atmospheric CO₂ and implications for carbon cycle research

Seth C. Olsen

Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, USA

James T. Randerson

Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, USA

Abstract

We used a three-dimensional atmospheric transport model to investigate several aspects of column CO₂ that are important for the design of new satellite-based observation systems and for the interpretation of observations collected by Sun-viewing spectrometers. These aspects included the amplitude of the diurnal cycle and how it is related to surface fluxes, the amplitude and phase of the seasonal cycle, and the magnitude of the north-south hemispheric gradient. In our simulation, we found that column CO₂ had less variability than surface CO₂ on all scales. The annual mean column CO₂ north-south gradient and seasonal cycle amplitude were approximately one half of their surface counterparts and the column CO₂ diurnal amplitude rarely exceeded 1 ppm. A 1 Gt C yr⁻¹ Northern Hemisphere carbon sink decreased the north-south column CO₂ gradient by ∼0.4 ppm.

Received 9 July 2003; accepted 29 October 2003; published 16 January 2004.

Index Terms: 0315 Atmospheric Composition and Structure: Biosphere/atmosphere interactions; 0368 Atmospheric Composition and Structure: Troposphere—constituent transport and chemistry; 1610 Global Change: Atmosphere (0315, 0325); 1615 Global Change: Biogeochemical processes (4805).

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Citation: Olsen, S. C., and J. T. Randerson (2004), Differences between surface and column atmospheric CO₂ and implications for carbon cycle research, J. Geophys. Res., 109, D02301, doi:10.1029/2003JD003968.

Copyright 2004 by the American Geophysical Union.