Estimates of Spatially and Temporally Resolved Constrained Organic Matter and Sulfur Dioxide Emissions Over the Indian Region Through the Strategic Source Constraints Modelling

A reliable present-day database of aerosol emissions discharged into the atmosphere is required in aerosol-climate models to accurately predict the atmospheric aerosol burden and provide necessary information for developing air quality and climate policies.Here we present the newly derived spatially and temporally resolved constrained sulfur dioxide (SO2) and organic matter (OM) emissions over the Indian region.The derivation was done by constraining the scattering to absorbing aerosols with the simulated fields of aerosol single scattering albedo (SSA) in the general circulation model of Laboratoire de Météorologie Dynamique (LMDZT-GCM). The annual emission rate of the constrained OM and SO2 emission over the Indian region were estimated as 8,422Ggyr-1 and 23,765Ggyr-1, respectively.The annual constrained OM and SO2 emitted over the Indo-Gangetic plain (central India) comprised about 55% (37%) and 45% (44%) of their total emission strength over the Indian subcontinent, respectively.The constrained SO2 emission (1609–2474 Gg) exhibited a relatively lower monthly variability than the OM emission (197–1182 Gg), with the highest (lowest) OM and SO2 monthly emission being, respectively, during March (July) and February (July).The distinct spatial and temporal changes in SO2 and OM emissions, as depicted from the z-score mapping, were governed by the change in their emission strength mainly from the fossil fuel (viz.industrial sector) and biomass combustion (viz.forest and crop-waste), respectively.The annual emission rate of constrained BC emission from the industrial sector (219Gg yr-1) and that of OM from the domestic sector(4211Gg yr-1) resembled well the recent bottom-up emission over India. The missing amount of source-sector-wide bottom-up emissions were identified by comparing the constrained with bottom-up emissions for reconciliation.