Source identification of aerosols influencing atmospheric extinction: Integrating PMF and PSCF with emission inventories and satellite observations

The relative influence of source categories of aerosols that affect atmospheric extinction is analyzed by evaluating the potential source contribution function (PSCF) based source regions of the positive matrix factorization (PMF) estimated factors against satellite retrievals of aerosol index and active fires and combining with emission inventory information. This approach has been applied to aerosol chemical data obtained from the integrated campaign undertaken during March-May 2006: Integrated Campaign for Aerosols, Gases and Radiation Budget (ICARB). Four source categories were identified: dust, nitrate-and-dust, biomass-and-fossil combustion, and secondary species. The relative influence of dust and nitrate-and-dust was higher during north-south transport from west Asia over the Arabian Sea during the period of campaign, coincident with highs in the spatial distribution of Ultraviolet Aerosol Index (UVAI) from the Ozone Monitoring Instrument (OMI), implying dust-nitrate association in the outflow from west Asia. The relative influence of anthropogenic sources (biomass-and-fossil combustion and secondary species) was higher over Bay of Bengal during March-April 2006. High fire frequency from the Moderate Resolution Imaging Spectroradiometer (MODIS), coincident with the probable source regions identified in the central Indo-Gangetic plain and central India (south of 27 degrees N), indicates influence of biomass burning source. The biomass-and-fossil combustion factor arising from biofuel, crop residue, and forest fires is evident by their large emission flux rather than from industrial sources in the probable source regions associated with this factor. In contrast, thermal power plant and industries largely influenced the secondary species factor. This approach provides verification of source categories identified through PMF against active sources from satellite remote sensing and provides an estimate of their relative strength based on emission inventory information.