Z-Z. Hu, S.I. Kuzmina,
L. Bengtsson, and D.M. Holland, 2003:
Mean and uncertainty of Arctic sea-ice change
and their connection with Arctic climate change in CMIP2 simulations,
COLA Technical Report No. 152, Center for
Ocean-Atmosphere-Land Studies, Calverton, Maryland USA, 31 pp.
Abstract
In this work, we analyze the two-dimensional
distribution of mean and uncertainty of Arctic sea-ice and climate change
at time of CO2 doubling and their connection using the simulations of the
second phase of the Coupled Model Intercomparison Project (CMIP2). Comparison
with observations shows that the ensemble mean of CMIP2 models simulates
the observed sea-ice climatology reasonable well. Arctic surface
warming at the time of CO2 doubling is not evenly-distributed and ranges
from 1 C to 5 C. The intermodel spread is pronounced in the Arctic
Ocean, particularly
in the Barents Sea. Reduction of sea-ice
thickness is in the range 0.3-1.8 m and mainly appears in the Greenland-Barents
Seas. Meanwhile, sea-ice concentrations decrease more than 10% in
most regions of the Arctic Ocean. The sensitivity of Arctic surface air
temperature change with respect to sea-ice area change is model dependent.
For some models, the sensitivity is different even in different periods
of the transient integration.
Values of the sensitivity vary from -2.0
to -0.5 C/10^6 km^2 for most CMIP2 models. Furthermore, colder (warmer)
Arctic climate may favor higher (lower) sensitivity.
Simulated mean and intermodel spread patterns
of surface air temperature change are similar to those of sea-ice thickness
and sea level pressure changes, implying that the mean and uncertainty
of projected Arctic climate change may be largely determined by the interaction
between sea-ice and the atmosphere. Both sea-ice thickness and sea-ice
concentration are sensitive to the increase in greenhouse gas concentrations,
and are connected with surface air temperature and sea level pressure changes
in the Arctic. The average of all model simulations indicates that a positive
phase of the Arctic Oscillation is stronger and/or occurs more often at
the time of CO2 doubling. Both the mean and intermodel spread patterns
show considerable differences between models with and without flux adjustment
in some regions.
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