Optical Characteristics and Radiative Effects of Anthropogenic and Natural Aerosols Over an Urban Area

Understanding aerosols is paramount, as an inadequate grasp of their properties and their variations across time and space could lead to irreversible consequences, with the potential for an overwhelming surge in atmospheric particle levels. Within the realm of aerosols, anthropogenic types, encompassing water-soluble aerosols and black carbon, hold sway over the “optical depth,” while natural aerosols, such as mineral dust and sea salt, dominate in terms of aerosol mass concentration. Empirical evidence confirms that black carbon aerosols play a substantial role in regional-scale global warming, contributing over 65% to the annual net atmospheric forcing. Moreover, black carbon aerosols significantly contribute to solar dimming, constituting 50% or more of radiative forcing at the Earth’s surface. The marked surface forcing and atmospheric warming induced by black carbon aerosols may exert a pronounced influence on the hydrological cycle. Tropospheric aerosols wield a substantial impact on the Earth’s climate, spanning local, regional, and global scales. In the atmospheric aerosol spectrum, two distinct categories emerge fine and coarse modes. Coarse mode aerosols, such as wind-borne mineral dust and sea salt particles, predominantly emanate from natural sources, while fine mode aerosols, prevalent over urban, industrialized, and densely populated regions, predominantly result from gas-to-particle conversion mechanisms stemming from activities like fossil fuel and biomass combustion, as well as other anthropogenic sources. The combustion of fossil fuels, particularly coal and biomass, has been identified as the leading contributor to global emissions.