Arctic climate response to forcing from light-absorbing particles in snow and sea ice in CESM 1Department of Atmospheric Sciences, P.O. Box 351640, University of Washington, Seattle, WA 98195, USA
05 Sep 2012
2Joint Institute for the Study of Atmosphere and Ocean, 3737 Brooklyn Ave NE, Seattle, WA 98195, USA
3National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307, USA
4Applied Physics Laboratory, Polar Science Center, Box 355640, University of Washington, Seattle, WA 98105, USA
Received: 31 Dec 2011 – Published in Atmos. Chem. Phys. Discuss.: 20 Feb 2012 Abstract. The presence of light-absorbing aerosol particles deposited on arctic snow
and sea ice influences the surface albedo, causing greater shortwave
absorption, warming, and loss of snow and sea ice, lowering the albedo
further. The Community Earth System Model version 1 (CESM1) now includes the
radiative effects of light-absorbing particles in snow on land and sea ice
and in sea ice itself. We investigate the model response to the deposition of
black carbon and dust to both snow and sea ice. For these purposes we employ
a slab ocean version of CESM1, using the Community Atmosphere Model version 4
(CAM4), run to equilibrium for year 2000 levels of CO2 and fixed aerosol
deposition. We construct experiments with and without aerosol deposition,
with dust or black carbon deposition alone, and with varying quantities of
black carbon and dust to approximate year 1850 and 2000 deposition fluxes.
The year 2000 deposition fluxes of both dust and black carbon cause
1–2 °C of surface warming over large areas of the Arctic Ocean and
sub-Arctic seas in autumn and winter and in patches of Northern land in every
season. Atmospheric circulation changes are a key component of the
surface-warming pattern. Arctic sea ice thins by on average about 30 cm.
Simulations with year 1850 aerosol deposition are not substantially different
from those with year 2000 deposition, given constant levels of CO2. The
climatic impact of particulate impurities deposited over land exceeds that of
particles deposited over sea ice. Even the surface warming over the sea ice
and sea ice thinning depends more upon light-absorbing particles deposited
over land. For CO2 doubled relative to year 2000 levels, the climate
impact of particulate impurities in snow and sea ice is substantially lower
than for the year 2000 equilibrium simulation.
Revised: 07 Jul 2012 – Accepted: 11 Aug 2012 – Published: 05 Sep 2012
Citation: Goldenson, N., Doherty, S. J., Bitz, C. M., Holland, M. M., Light, B., and Conley, A. J.: Arctic climate response to forcing from light-absorbing particles in snow and sea ice in CESM, Atmos. Chem. Phys., 12, 7903-7920, doi:10.5194/acp-12-7903-2012, 2012.