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Estimated range of black carbon dry deposition and the related snow albedo reduction over Himalayan glaciers during dry pre-monsoon periods
Abstract One of the major factors attributed to the accelerated melting of Himalayan glaciers is the snow darkening effect of atmospheric black carbon (BC). The BC is the result of incomplete fossil fuel combustion from sources such as open biomass burning and wood burning cooking stoves. One of the key challenges in determining the darkening effect is the estimation uncertainty of BC deposition (BCD) rate on surface snow cover. Here we analyze the variation of BC dry deposition in seven different estimates based on different dry deposition methods which include different atmospheric forcings (observations and global model outputs) and different spatial resolutions. The seven simulations are used to estimate the uncertainty range of BC dry deposition over the southern Himalayas during pre-monsoon period (March–May) in 2006. Our results show BC dry deposition rates in a wide range of 270–4700 μg m−2 during the period. Two global models generate higher BC dry deposition rates due to modeled stronger surface wind and simplification of complicated sub-grid surface conditions in this region. Using ice surface roughness and observation-based meteorological data, we estimate a better range of BC dry deposition rate of 900–1300 μg m−2. Under dry and highly polluted conditions, aged snow and sulfate-coated BC are expected to possibly reduce visible albedo by 4.2–5.1%. Our results suggest that for estimating aerosol-induced snow darkening effects of Himalaya snowpacks using global and regional models, realistic physical representation of ice or snow surface roughness and surface wind speed are critical in reducing uncertainties on the estimate of BC deposition over snow surface.
Highlights ► Black carbon emission is significant over Indo-Gangetic Plain. ► We estimated possible wider range of black carbon dry deposition over the southern Himalayas. ► Its impact on snow albedo reductions over Himalayan glaciers was also estimated. ► Surface wind and roughness affect the deposition amount and snow albedo reduction. ► Surface parameterization in transport model is important for their accurate estimate.
Estimated range of black carbon dry deposition and the related snow albedo reduction over Himalayan glaciers during dry pre-monsoon periods
Abstract One of the major factors attributed to the accelerated melting of Himalayan glaciers is the snow darkening effect of atmospheric black carbon (BC). The BC is the result of incomplete fossil fuel combustion from sources such as open biomass burning and wood burning cooking stoves. One of the key challenges in determining the darkening effect is the estimation uncertainty of BC deposition (BCD) rate on surface snow cover. Here we analyze the variation of BC dry deposition in seven different estimates based on different dry deposition methods which include different atmospheric forcings (observations and global model outputs) and different spatial resolutions. The seven simulations are used to estimate the uncertainty range of BC dry deposition over the southern Himalayas during pre-monsoon period (March–May) in 2006. Our results show BC dry deposition rates in a wide range of 270–4700 μg m−2 during the period. Two global models generate higher BC dry deposition rates due to modeled stronger surface wind and simplification of complicated sub-grid surface conditions in this region. Using ice surface roughness and observation-based meteorological data, we estimate a better range of BC dry deposition rate of 900–1300 μg m−2. Under dry and highly polluted conditions, aged snow and sulfate-coated BC are expected to possibly reduce visible albedo by 4.2–5.1%. Our results suggest that for estimating aerosol-induced snow darkening effects of Himalaya snowpacks using global and regional models, realistic physical representation of ice or snow surface roughness and surface wind speed are critical in reducing uncertainties on the estimate of BC deposition over snow surface.
Highlights ► Black carbon emission is significant over Indo-Gangetic Plain. ► We estimated possible wider range of black carbon dry deposition over the southern Himalayas. ► Its impact on snow albedo reductions over Himalayan glaciers was also estimated. ► Surface wind and roughness affect the deposition amount and snow albedo reduction. ► Surface parameterization in transport model is important for their accurate estimate.
Estimated range of black carbon dry deposition and the related snow albedo reduction over Himalayan glaciers during dry pre-monsoon periods
Yasunari, Teppei J. (author) / Tan, Qian (author) / Lau, K.-M. (author) / Bonasoni, Paolo (author) / Marinoni, Angela (author) / Laj, Paolo (author) / Ménégoz, Martin (author) / Takemura, Toshihiko (author) / Chin, Mian (author)
Atmospheric Environment ; 78 ; 259-267
2012-03-09
9 pages
Article (Journal)
Electronic Resource
English
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