Sources of carbon monoxide and formaldehyde in North America determined from high-resolution atmospheric data
1Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA
2Department of Environmental Science, Policy and Management, University of California Berkeley, Berkeley, CA, USA
3NOAA Earth Systems Research Laboratory, Global Monitoring Division, Boulder, CO, USA
4Department of Soil, Water, and Climate, University of Minnesota, St. Paul, MN, USA
5Max-Planck Institute for Biogeochemistry, Jena, Germany
6Dept. of Earth and Environmental Sciences, University of Waterloo, Waterloo, ON, Canada
7National Laboratory of Scientific Computing, Petropolis, Brazil
Abstract. We analyze the North American budget for carbon monoxide using data for CO and formaldehyde concentrations from tall towers and aircraft in a model-data assimilation framework. The Stochastic Time-Inverted, Lagrangian Transport model for CO (STILT-CO) determines local to regional-scale CO contributions associated with production from fossil fuel combustion, biomass burning, and oxidation of volatile organic compounds (VOCs) using an ensemble of Lagrangian particles driven by high resolution assimilated meteorology. In most cases, the model demonstrates high fidelity simulations of hourly surface data from tall towers and point measurements from aircraft, with somewhat less satisfactory performance in coastal regions and when CO from large biomass fires in Alaska and the Yukon Territory influence the continental US.
Inversions of STILT-CO simulations for CO and formaldehyde show that current inventories of CO emissions from fossil fuel combustion are significantly too high, by almost a factor of three in summer and a factor two in early spring, consistent with recent analyses of data from the INTEX-A aircraft program. Formaldehyde data help to show that sources of CO from oxidation of CH4 and other VOCs represent the dominant sources of CO over North America in summer.