A fifteen year record of CO emissions constrained by MOPITT CO observations
Zhe Jiang1,2, John R. Worden1, Helen Worden2, Merritt Deeter2, Dylan B. A. Jones3, Avelino F. Arellano4, and Daven K. Henze51Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA 2National Center for Atmospheric Research, Boulder, CO, USA 3Department of Physics, University of Toronto, Toronto, ON, Canada 4Department of Hydrology and Atmospheric Sciences, University of Arizona, Tucson, AZ, USA 5Department of Mechanical Engineering, University of Colorado, Boulder, CO, USA
Received: 11 Sep 2016 – Accepted for review: 05 Oct 2016 – Discussion started: 17 Oct 2016
Abstract. Long-term measurements from satellites and surface stations have demonstrated a decreasing trend of tropospheric carbon monoxide (CO) in the Northern Hemisphere over the past decade. Likely explanations for this decrease include changes in anthropogenic, fires, and/or biogenic emissions or changes in the primary chemical sink hydroxyl radical (OH). Using remotely sensed CO measurements from the Measurement of Pollution in the Troposphere (MOPITT) satellite instrument, in-situ methyl chloroform (MCF) measurements from World Data Centre for Greenhouse Gases (WDCGG), and the adjoint of the GEOS-Chem model, we estimate the change in global CO emissions from 2001–2015. We show that the loss rate of MCF varies by 0.2 % in the past 15 years, indicating that changes in global OH distributions do not explain the recent decrease in CO. Our two-step inversion approach for estimating CO emissions is intended to mitigate the effect of bias errors in the MOPITT data as well as model errors in transport and chemistry, which are the primary uncertainties when quantifying CO emissions using these remotely sensed data. Our results confirm that the decreasing trend of tropospheric CO in the Northern Hemisphere is due to decreasing CO emissions from anthropogenic and biomass burning sources. In particular, we find decreasing CO emissions from the United States and China in the past 15 years, unchanged anthropogenic CO emissions from Europe since 2008, and likely a positive trend from India and southeast Asia, in contrast to recently reported results. We find decreasing trends of biomass burning CO emissions from boreal North America, boreal Asia and South America, but little change over Africa. The inconsistency between our analysis with recent study suggests more efforts are needed for robust conclusion about the variation of anthropogenic CO emissions for India and Southeast Asia.
Jiang, Z., Worden, J. R., Worden, H., Deeter, M., Jones, D. B. A., Arellano, A. F., and Henze, D. K.: A fifteen year record of CO emissions constrained by MOPITT CO observations, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2016-811, in review, 2016.