HR: 1330h
AN: A52B-0782    [PDF]
TI: Differences Between Surface and Column CO$_2$ Variability and Implications for Carbon Cycle Research
AU: * Olsen, S C
EM: olsen@gps.caltech.edu
AF: Division of Geological and Planetary Science, California Institute of Technology, Pasadena, CA 91125 United States
AU: Randerson, J T
EM: jimr@gps.caltech.edu
AF: Department of Earth System Science, University of California at Irvine, Irvine, CA 92697
AB: While diurnal, seasonal, and latitudinal aspects of CO$_2$ variability have been extensively explored near the surface, much less is known about the behavior of the CO$_2$ column integral. Understanding the modes of variability in column CO$_2$ is critical for the design and interpretation of new upward looking and satellite-based CO$_2$ spectrometers. We used a three dimensional atmospheric transport model to investigate key aspects of column CO$_2$, including 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 CO$_2$ had less variability than surface CO$_2$ on all scales. The annual mean column CO$_2$ north-south gradient and seasonal cycle amplitude were approximately one half of their surface counterparts and the column CO$_2$ diurnal amplitude rarely exceeded 1 ppm. A 1 Gt C yr$^{-1}$ northern hemisphere carbon sink decreased the north-south column CO$_2$ gradient by $\sim$0.4 ppm.
DE: 0315 Biosphere/atmosphere interactions
DE: 0322 Constituent sources and sinks
DE: 0368 Troposphere--constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting