| Summary: | Snow and ice cover a significant portion of the Earth’s surface, and not only provide fresh water to billions of people, but also contribute to the Earth’s energy balance through a high surface albedo, reflecting most incident solar radiation back towards space. The surface albedo and reflected radiation can be greatly reduced by small amounts of light-absorbing impurities within the snowpack, such as black carbon (BC), mineral dust aerosol, and microbial growth. A wealth of observations and modelling of snow optical and radiative properties recognize BC and mineral dust aerosol as dominating the reduction of snow albedo after deposition, but growing research into atmospheric, light-absorbing organic carbon (OC) aerosol, known as brown carbon (BrC), encourages a greater understanding of the impacts of this impurity in the snowpack. Little is known about how BrC deposition onto snow surfaces affects the spectral snow albedo and what radiative forcing results from BrC deposition. This is of special importance for areas of the Arctic where wildfires burn fuels, such as peat, that emit BrC aerosol in close proximity to snow and ice. The goal of this dissertation is to explore this snow-BrC aerosol relationship. A simple apparatus was developed to generate and deposit aerosols onto a snow surface to study aerosol deposition and its effect on snow albedo experimentally and to compare with theory. This portable apparatus was used to deposit combustion and mineral dust aerosol – including black carbon, brown carbon, and hematite – in situ onto snow surfaces. Aerosols were generated and continuously transported into a deposition chamber placed on the snow surface, where there were evenly deposited, thereby modifying the snowpack’s optical and radiative properties. Field operation of this apparatus was demonstrated and changes in snow surface reflectivity were monitored by measuring the spectral directional reflectance of the deposited areas and of adjacent natural snowpack. The apparatus was further used for the ...
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