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Title: The influence of cloud and surface properties on the Arctic Ocean shortwave radiation budget in coupled models (vol 21, pg 866, 2008)
Authors: Gorodetskaya, Irina
Tremblay, L. -Bruno
Liepert, Beate
Cane, Mark A
Cullather, Richard I #
Issue Date: 2008
Publisher: American Meteorological Society
Series Title: Journal of Climate vol:21 issue:12 pages:3078-3078
Abstract: The impact of Arctic sea ice concentrations, surface albedo, cloud fraction, and cloud ice and liquid water
paths on the surface shortwave (SW) radiation budget is analyzed in the twentieth-century simulations of
three coupled models participating in the Intergovernmental Panel on Climate Change Fourth Assessment
Report. The models are the Goddard Institute for Space Studies Model E-R (GISS-ER), the Met Office
Third Hadley Centre Coupled Ocean–Atmosphere GCM (UKMO HadCM3), and the National Center for
Atmosphere Research Community Climate System Model, version 3 (NCAR CCSM3). In agreement with
observations, the models all have high Arctic mean cloud fractions in summer; however, large differences
are found in the cloud ice and liquid water contents. The simulated Arctic clouds of CCSM3 have the
highest liquid water content, greatly exceeding the values observed during the Surface Heat Budget of the
Arctic Ocean (SHEBA) campaign. Both GISS-ER and HadCM3 lack liquid water and have excessive ice
amounts in Arctic clouds compared to SHEBA observations. In CCSM3, the high surface albedo and strong
cloud SW radiative forcing both significantly decrease the amount of SW radiation absorbed by the Arctic
Ocean surface during the summer. In the GISS-ER and HadCM3 models, the surface and cloud effects
compensate one another: GISS-ER has both a higher summer surface albedo and a larger surface incoming
SW flux when compared to HadCM3. Because of the differences in the models’ cloud and surface properties,
the Arctic Ocean surface gains about 20% and 40% more solar energy during the melt period in the
GISS-ER and HadCM3 models, respectively, compared to CCSM3.
In twenty-first-century climate runs, discrepancies in the surface net SW flux partly explain the range in
the models’ sea ice area changes. Substantial decrease in sea ice area simulated during the twenty-first
century in CCSM3 is associated with a large drop in surface albedo that is only partly compensated by
increased cloud SW forcing. In this model, an initially high cloud liquid water content reduces the effect of
the increase in cloud fraction and cloud liquid water on the cloud optical thickness, limiting the ability of
clouds to compensate for the large surface albedo decrease. In HadCM3 and GISS-ER, the compensation
of the surface albedo and cloud SW forcing results in negligible changes in the net SW flux and is one of
the factors explaining moderate future sea ice area trends. Thus, model representations of cloud properties
for today’s climate determine the ability of clouds to compensate for the effect of surface albedo decrease
on the future shortwave radiative budget of the Arctic Ocean and, as a consequence, the sea ice mass balance.
Description: Correction
ISSN: 0894-8755
Publication status: published
KU Leuven publication type: DI
Appears in Collections:Non-KU Leuven Association publications
# (joint) last author

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