Inverse Model Estimates of Global Carbon Monoxide Emissions Using GMD Network Observations

We present an inverse analysis of global CO emissions by using network observations from NOAA's Global Monitoring Division (GMD) and a global three-demensional atmospheric chemical transport model (GEOS- CHEM) simulation from 1997-2005. A priori estimates of CO emissions are taken from various inventories, including the GFED2 biomass burning emission inventory. The modeled CO mixing ratio are then compared with the observation at 71 GMD stations. Our inverse analysis focuses on the robustness of the a posteriori source estimates by assessing the sensitivity to statistical assumptions of errors. We also consider results from other transport models and MOPITT CO measurements in our analysis. We then use our best estimates to evaluate the contribution of fires to interannual variations in global carbon dioxide and methane growth rates.