Estimated impact of black carbon deposition during pre-monsoon season from Nepal Climate Observatory – Pyramid data and snow albedo changes over Himalayan glaciers

The possible minimal range of reduction in snow surface albedo due to dry deposition of black carbon (BC) in the pre-monsoon period (March–May) was estimated as a lower bound together with the estimation of its accuracy, based on atmospheric observations at the Nepal Climate Observatory – Pyramid (NCO-P) sited at 5079 m a.s.l. in the Himalayan region. A total BC deposition rate was estimated as 2.89 µg m-2 day -1 providing a total deposition of 266 µg m-2 for March–May at the site, based on a calculation with a minimal deposition velocity of (1.0×10 (-4) m s( -1)) with atmospheric data of equivalent BC concentration. Main BC size at NCO-P site was determined as 103.1–669.8 nm by correlation analyses between equivalent BC concentration and particulate size distributions in the atmosphere. The BC deposition from the size distribution data was also estimated. Itwas found that 8.7% of the estimated dry deposition corresponds to the estimated BC deposition from equivalent BC concentration data. If all the BC is deposited uniformly on the top 2-cm pure snow, the corresponding BC concentration is 26.0–68.2 µg kg-1, assuming snow density variations of 195–512 kg m-3 of Yala Glacier close to NCO-P site. Such a concentration of BC in snow could result in 2.0–5.2% albedo reductions. By assuming these albedo reductions continue throughout the year, and then applying simple numerical experiments with a glacier mass balance model, we estimated reductions would lead to runoff increases of 70–204 mm of water. This runoff is the equivalent of 11.6–33.9% of the annual discharge of a typical Tibetan glacier. Our estimates of BC concentration in snow surface for pre-monsoon season is comparable to those at similar altitudes in the Himalayan region, where glaciers and perpetual snow regions begin, in the vicinity of NCO-P. Our estimates from only BC are likely to represent a lower bound for snow albedo reductions, because we used a fixed slower deposition velocity. In addition, we excluded the effects of atmospheric wind and turbulence, snow aging, dust deposition, and snow albedo feedbacks. This preliminary study represents the first investigation of BC deposition and related albedo on snow, using atmospheric aerosol data observed at the southern slope in the Himalayas.

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Teppei J. Yasunari (NASA Goddard Space Flight Center,) - Paolo Bonasoni (Institute of Atmospheric Sciences and Climate (ISAC) - CNR) - Paolo Laj (CNRS Laboratory of Meteorology Physics - Laboratory of Glaciology) - Angela Marinoni (Institute of Atmospheric Sciences and Climate (ISAC) - CNR) - Paolo Cristofanelli (Institute of Atmospheric Sciences and Climate (ISAC) - CNR) - Elisa Vuillermoz (Ev-K2-CNR) - Rocco Duchi (Institute of Atmospheric Sciences and Climate (ISAC) - CNR) - Gianni Tartari (The Water Research Institute (IRSA)-CNR) - William K.-M. Lau (NASA Goddard Space Flight Center,) - Koji Fujita (Graduate School of Environmental Studies, Nagoya University) (2010) . Estimated impact of black carbon deposition during pre-monsoon season from Nepal Climate Observatory – Pyramid data and snow albedo changes over Himalayan glaciers. Copernicus GmbH (Copernicus Publications) https://geoportal.mountaingenius.org/geonetwork/srv/api/records/a1f78238-cb81-4b13-b9de-974c1deb1d05

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File identifier: a1f78238-cb81-4b13-b9de-974c1deb1d05 XML

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Climatology, meteorology, atmosphere
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Keywords ( Theme )

Atmospheric Brown Clouds

Keywords ( Place )

Himalayas , Nepal Climate Observatory-Pyramid , Nepal

Keywords ( Theme )

black carbon , snow surface albedo

Keywords ( Temporal )

pre-monsoon period

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Date ( Publication ): 2010-07-19T00:00:00

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The book contains the scientific papers by EvK2Cnr researchers in a special issue of Atmospheric Chemistry and Physics, entitled "Atmospheric brown clouds in the Himalayas "

"Estimated impact of black carbon deposition during pre-monsoon season from Nepal Climate Observatory -- Pyramid data and snow albedo changes over Himalayan glaciers". T. J. Yasunari, P. Bonasoni, P. Laj, K. Fujita, E. Vuillermoz, A. Marinoni, P. Cristofanelli, R. Duchi, G. Tartari, and K.-M. Lau. Atmos. Chem. Phys., 10, 6603-6615, 2010.