Atmos. Chem. Phys. Discuss., 9, 24875-24911, 2009
© Author(s) 2009. This work is distributed
under the Creative Commons Attribution 3.0 License.
Review Status
This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Analysis of global and regional CO burdens measured from space between 2000 and 2009 and validated by ground-based solar tracking spectrometers
L. N. Yurganov1, W. McMillan1, E. Grechko2, and A. Dzhola2
1Joint Center for Earth System Technology, University of Maryland Baltimore County, Baltimore, MD, USA
2Obukhov Institute of Atmospheric Physics, Moscow, Russia

Abstract. CO total column (TC) retrievals from MOPITT version 3 and AIRS version 5 are validated through comparisons with archived TC data from the Network for Detection of Atmospheric Composition Change (NDACC) ground-based Fourier Transform Spectrometers (FTS) between March 2000 and December 2007. MOPITT retrievals exhibit an increasing temporal bias with a rate of 1.4–1.8% per year; thus far, AIRS retrievals appear to be more stable. For the lowest CO values in the Southern Hemisphere (SH), AIRS TC retrievals overestimate FTS TC by 20%. MOPITT's bias and standard deviation do not depend on CO TC absolute values. Empirical corrections are derived for AIRS and MOPITT retrievals based on the observed annually averaged bias versus the FTS TC. With these corrections, CO burdens from AIRS and MOPITT come into good agreement in the mid-latitudes of the Northern Hemisphere (NH) and in the tropical belt. In the SH, agreement between AIRS and MOPITT CO burdens is better for the larger CO TC in austral winter and worse in austral summer when CO TC are smaller. Interannual variations in AIRS and MOPITT retrieved CO burdens are compared with CO emissions from wild fires from the Global Fire Emission Dataset (GFED2) inventory. Before July 2008, all variations in retrieved CO burden can be explained by changes in fire emissions. After July 2008, global and tropical CO burdens decreased until October before recovering by the beginning of 2009. The NH CO burden also decreased but reached a minimum in January 2009 before starting to recover. The decrease in tropical CO burdens is explained by lower than usual fire emissions in South America and Indonesia. This decrease in topical emissions also accounts for most of the change in global CO burden. However, no such diminution of NH biomass burning is indicated by GFED2. Thus, the CO burden decrease in the NH could result from a combination of lower fossil fuel emissions during the global economic recession and transport of less CO from the tropics. More extensive modeling will be required to fully resolve this issue.

Citation: Yurganov, L. N., McMillan, W., Grechko, E., and Dzhola, A.: Analysis of global and regional CO burdens measured from space between 2000 and 2009 and validated by ground-based solar tracking spectrometers, Atmos. Chem. Phys. Discuss., 9, 24875-24911, doi:10.5194/acpd-9-24875-2009, 2009.
Search ACPD
Discussion Paper
    Final Revised Paper