Long term trends in aerosol optical depth and related parameters over the eastern Indo-Gangetic plain

Rawat, Prashant (2018) Long term trends in aerosol optical depth and related parameters over the eastern Indo-Gangetic plain. Masters thesis, Indian Institute of Science Education and Research Kolkata.

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Abstract

Aerosols are solid and liquid particles suspended in air. Aerosols are so small yet their impact on health, climate, weather and ecology is very significant. In short, aerosols have the capacity to alter the solar radiation budget, to effect health, and climate which give rise to the necessity of measuring them from a local to global scale. We can study aerosols properties and their effect on climate by using several parameters in data provided from satellite. These parameters tell us about the amount of aerosols and their size based on which their effects can be determined. Even after playing a major role in atmospheric processes and possessing danger to human health, aerosols over Indian subcontinent are under studied or have been studied for s short time frame which lack in predicting a trend. Very few studies have been done on aerosol chemical components such as BC (black carbon) , OC (organic carbon), DU (dust), SS (sea-salt), SU (sulfate) and their trends over the years and their seasonal signatures. Due to very high emission from industries, vehicles, biomass burning, power plants, coal consumption, residual crop burning, production and loading of aerosol in Indian atmosphere has increased a lot over past time and expected to keep increasing in future too. The present study tried to establish monthly, seasonal, and yearly trends of AOD, AE and aerosol chemical components black carbon (BC), organic carbon (OC), dust (DU), sea-salt (SS), sulfate (SU) in the Eastern Indo-Gangetic Plain (EIGP); investigate relative contributions of aerosol chemical components to total aerosol light extinction in the EIGP; and identify potential source sectors of aerosols, and delineate contributions from local and regional sources. Our work shows that AOD values over the Greater Kolkata region have increased consistently over last 17 years indicating significant ongoing deterioration of air quality as majority of the aerosols are pollutants such as SU, BC, OC; light extinction by aerosols in this region is predominantly controlled by sulfate, BC and OC are also playing smaller roles towards the extinction of light; and there appears to exist a non-trivial regional component of sulfate, BC and OC originating in the central IGP that affects air quality over the Greater Kolkata region.

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