An inventory of gaseous and primary carbonaceous aerosol emissions from India for the Ganges Valley Aerosol Experiment (GVAX)

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Description

India is one of the most rapidly developing countries in the world. In the past decade, high aerosol concentrations and aerosol optical depth (AOD) values have been observed by both ground- and satellite-based measurements over this region, and increasing emissions in India have been reported to modify the regional climate through the direct and indirect radiative effects of aerosols. In this study, a new inventory of gaseous (SO2, NOx, and NMVOC) and primary carbonaceous aerosol (black and organic carbon, BC, and OC) emissions from India in 2010 is developed to support the Ganges Valley Aerosol Experiment (GVAX). A reliable emission inventory for the region is necessary to support atmospheric chemistry modeling, data analysis, and flight planning. In this inventory, the emission sources are categorized into five major sectors: power generation, industry, residential, transport, and open biomass burning. For SO2, BC, and OC, a detailed technology-based methodology is used to estimate emissions. Activity data are from the International Energy Agency (IEA) and various Indian national statistics. Emissions are first estimated for 2008 (the latest year for which actual activity data are available) and extrapolated to 2010 based on fast-track statistics. Emissions are then gridded at a resolution of 0.5° × 0.5° using up-to-date surrogate distributions, including the exact locations of all power generation units with capacity larger than 20 MW, urban and rural population, industrial GDP, road networks, crop land cover, etc. For NOx and NMVOC, sectoral gridded emissions from EDGAR4.1 in 2005 are used as a baseline and then extrapolated to 2010 according to appropriate scale factors such as the growth rates of energy consumption and GDP. EDGAR emissions will also be used for surrounding parts of the South Asian region. Our preliminary estimates of SO2, BC, and OC emissions for India are 8.83 Tg, 1.05 Tg, and 2.88 Tg, respectively, in 2010. Coal-fired power plants and traditional cookstoves are the main sources of SO2 and carbonaceous aerosols, respectively. Monte Carlo simulations are used to quantify the emission uncertainties, and the 95% confidence intervals are -16% to 18%, -40% to 77%, and -41% to 82% for SO2, BC, and OC, respectively. The major contributors to emissions uncertainty in India are coal sulfur content for SO2 (60%) and fuelwood emission factors of traditional cookstoves for BC (55%) and OC (61%).