HR: 1340h
AN: A33A-0838    [Abstracts]
TI: In-Situ Observations and Modeling of Black Carbon Aerosols in Arctic Snow
AU: Pedersen, C A
EM: xtina@npolar.no
AF: Norwegian Polar Institute, Polar Environmental Centre, Tromso, 9296, Norway
AU: * Gerland, S
EM: s.gerland@npolar.no
AF: Norwegian Polar Institute, Polar Environmental Centre, Tromso, 9296, Norway
AU: Berntsen, T K
EM: t.k.berntsen@geo.uio.no
AF: CICERO-Center for International Climate and Environmental Research Oslo, P.O. Box 1129 Blindern, Oslo, 0315, Norway
AU: Forsstrom, S
EM: sanja@npolar.no
AF: Norwegian Polar Institute, Polar Environmental Centre, Tromso, 9296, Norway
AU: Strom, J
EM: johan@itm.su.se
AF: Department of Applied Environmental Science, Stockholm University, Stockholm, 10691, Sweden
AU: Isaksson, E
EM: elli@npolar.no
AF: Norwegian Polar Institute, Polar Environmental Centre, Tromso, 9296, Norway
AB: Black Carbon (BC) particles emitted by fossil fuel and biomass combustion are transported to the Arctic and deposited in snow and ice, leading to reduced surface albedo and thus a warming of the climate. BC aerosols in the air have the direct effect of absorbing solar radiation, as well as semi direct and indirect effects on clouds. These mechanisms generally have a warming effect, but the activities that lead to emissions of BC also have associated emissions of other compounds, including some that have a cooling effect. The presentation is fourfold and details (i) BC concentrations on a regional scale and (ii) a local scale from snow samples, (iii) BC levels from modelling, and (iv) the relationship between BC and snow optical properties. The concentration of BC from snow in Norway (mainland), the Svalbard archipelago and the Arctic Ocean is determined from snow samples collected in the field, melted and filtered in the lab, and analysed for elemental carbon with a thermo- optical method. Chemical Transport Model calculations of the BC deposition at the observational sites during the relevant period leading up the observational period are performed to compare and validate the BC deposition in the model. Small scale studies concern BC concentrations as a function of altitude along a Svalbard glacier and of depth through the seasonal snow-pack. The optical properties of snow is affected by, most importantly, snow grain size, light conditions (clouds and solar height), snow thickness and impurities like BC, so it is not straightforward to derive the alteration from BC alone. To complicate the picture even more, BC particles can be embedded within the snow grains or the mixing can be external. This contribution tries to answer some of the uncertainties associated with BC in snow.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0700 CRYOSPHERE (4540)
DE: 0736 Snow (1827, 1863)
DE: 1621 Cryospheric change (0776)
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting