Walsh, J.E., V. M. Kattsov,
W. L. Chapman,V. Govorkova, and T. Pavlova, 2002:
Comparison of Arctic climate simulations
by uncoupled and coupled global models
Journal of Climate,
15,
1429-1446.
ABSTRACT
Simulations of present-day Arctic climate
are assessed from suites of (1) thirteen global atmosphere-only models
from the Atmospheric Model Intercomparison Project (AMIP-II) and (2) eight
coupled atmosphere-ocean-ice models from the Data Distribution Center of
the Intergovernmental Panel on Climate Change (IPCC). The assessment highlights
the impact of coupling on the simulated Arctic climate, and also the improvement
of the uncoupled models relative to a previous (early 1990s) phase of the
AMIP project. The across-model variance of the simulated air temperature
is larger in the coupled models than in the uncoupled models, and the spatial
pattern of the variance indicates that differences in the coupled models'
simulated sea ice contribute to the larger variance of temperature.
The coupled models are also several degrees warmer than the uncoupled models
during the winter half of the year. As was the case with the earlier
AMIP models, the simulated precipitation still exceeds the observational
estimates, particularly over the terrestrial watersheds of the Arctic Ocean.
The bias is larger in the coupled models and is strongest during the cold
season. Both the coupled and the uncoupled models suffer from a bias
of Arctic sea level pressure that will adversely impact the simulated sea
ice motion and the ice thickness distribution. The bias appears as
a shift of mass from the Beaufort sector of the Arctic Ocean to the Asian
coastal seas. Improvements in simulated cloud coverage from AMIP-I
to AMIP-II are apparent in a reduction of the across-model scatter of the
AMIP-II cloud coverage and also in a more realistic annual cycle of the
cloud fraction composited over the AMIP-II models. The Arctic surface
radiative fluxes vary widely among the AMIP-II models, especially under
cloudy skies.