Greenhouse gases stabilizing winter atmosphere in the Indo-Gangetic plains may increase aerosol loading

The concentration of aerosols along the Indo-Gangetic Plains (IGP) and their adverse effects on human health and the environment are increasing, particularly in winter, when the IGP is prone to high anthropogenic aerosol loading (i.e. particulate matter – PM). In this study, three reanalysis datasets including the MERRA aerosol reanalysis were analyzed to characterize the relationship between winter atmospheric stability and aerosols. Due to the lack of long-term aerosol observations, an empirical relationship between PM and the atmospheric temperature lapse rate was derived. It is shown that PM and stability have a strong relationship at the lower troposphere. Analyses of Coupled Model Intercomparison Project (CMIP5) single-forcing experiments indicate that the recent stabilization of the atmosphere in the IGP can be explained by both greenhouse gas (GHG) and aerosol forcings. Since a more stable atmosphere traps more PM, stabilization alone can increase aerosols even in the absence of changes in emission sources. Regional simulation with fixed anthropogenic aerosol loading also supports this finding. Thus, enhanced stabilization caused by both aerosols and GHG in the atmosphere can further increase winter aerosol loading in the IGP.