INTERPRETING SATELLITE REMOTE SENSING, AIRCRAFT AND GROUND-BASED OBSERVATIONS OF AEROSOL USING A CHEMICAL TRANSPORT MODEL

Abstract

Fine particulate matter (PM2.5) is the leading environmental risk factor for the global burden of disease. Black carbon (BC) and metal components are primarily responsible for the adverse health effects associated with PM2.5. PM2.5 also has climate effects, especially BC that contributes significantly to Arctic warming. We interpret satellite, aircraft, and ground-based measurements using the GEOS-Chem global chemical transport model to better understand PM2.5 and its chemical composition. We determine and interpret PM2.5 concentrations over eastern China for 2013 from aerosol optical depth (AOD) retrieved by the new Korean geostationary ocean color imager (GOCI) satellite instrument. Significant agreement is found between GOCI-derived PM2.5 and ground-based measurements in both annual averages (R2 =0.66, N = 494) and monthly averages (relative RMSE = 18.3 %). Secondary inorganics (SO42−, NO3−, NH4+) and organic matter are the most important components of GOCI-derived PM2.5. The population-weighted GOCI-derived PM2.5 over eastern China for 2013 is 53.8 μg m−3, with 400 million residents in regions that exceed the Interim Target-1 of the World Health Organization. We interpret a series of recent airborne and ground-based measurements with the GEOS-Chem model and its adjoint to attribute the sources of Arctic BC. We find that anthropogenic emissions from eastern and southern Asia have the largest impact on the Arctic BC column burden (~37%) and that anthropogenic emissions from northern Asia are the primary source of the Arctic surface BC (~40%). Our adjoint simulations indicate noteworthy contributions from emissions in eastern China (15 %) and western Siberia (6.5 %) to the Arctic BC column concentrations. Gas flaring emissions from oilfields in western Siberia could have a striking impact (13 %) on Arctic BC loadings in January. We present an initial simulation of 12 trace metals: Si, Ca, Al, Fe, Ti, Mn, K, Mg, As, Cd, Ni and Pb over continental North America for 2013 at a fine resolution of 0.25 ° x 0.3125 ° by using the GEOS-Chem transport model. The evaluation of modeled trace metal concentrations with observations from more than 200 monitors across North America indicates a promising spatial consistency.