Assessment of the Sources of Black Carbon and Carbon Monoxide using OMI Aerosol Absorption Optical Depth, MOPITT Carbon Monoxide, and the adjoint of GEOS-Chem

Abstract:

Black carbon (BC) and carbon monoxide (CO) are byproducts of incomplete combustion from similar sources but their emission ratio varies significantly between sources. Accurate estimates of the emissions and distribution of BC and CO are critical to studies of the atmospheric environment and climate change. We attempt to reduce uncertainties in BC emissions and improve BC model simulations by developing top-down, spatially resolved, estimates of BC emissions through assimilation of OMI observations aerosol absorption optical depth (AAOD) over Southeast Asian (70°E–150°E, 11°S–55°N) with the GEOS-Chem model. The impacts of different inversion approaches (scaling factor based and emission based), observation operators, a priori constraints and resolution errors on the optimization are investigated and discussed. A remarkable correlation between BC and CO has been found in a number of studies of in situ measurements or model results, and the source-specific emission ratios are an important constraint on global climate and regional air quality models. We thus diagnose these correlations with satellite observations by analyzing the long-term OMI AAOD and MOPITT CO from 2005 to 2013 to investigate the AAOD/CO ratio in seasonal and inter annual scale to assess the seasonal variability and long-term trends of BC and CO sources, including the major emissions sources of anthropogenic activities by sectors and biomass mass burning emissions. The strengths and deficiencies of simulated AAOD/CO ratio using global chemical transport model GEOS-Chem are discovered and compared to the observed AAOD/CO ratio to quantify the biases and uncertainties of corresponding emission sources of BC and CO.