Li, L., J. L. McClean, A. J. Miller, I. Eisenman, M. C. Hendershott
and C. A. Papadopoulos, 2014:
Processes driving sea ice variability in the Bering Sea in an eddying
ocean/sea ice model: Mean seasonal cycle
Ocean Modelling, 84, 51-66.
Abstract.
The seasonal cycle of sea ice variability in the Bering Sea, together with the
thermodynamic and dynamic processes that control it, are examined in a fine resolution
(1/10 deg) global coupled ocean/sea-ice model configured in the Community Earth System
Model (CESM) framework. The ocean/sea-ice model consists of the Los Alamos
National Laboratory Parallel Ocean Program (POP) and the Los Alamos Sea Ice Model
(CICE). The model was forced with time-varying reanalysis atmospheric forcing for the
time period 1980-1989. The simulated seasonal-mean fields of sea ice concentration
strongly resemble satellite-derived observations, as quantified by root-mean-square errors
and pattern correlation coefficients. The sea ice energy budget reveals that the seasonal
thermodynamic ice volume changes are dominated by the surface energy flux between
the atmosphere and the ice in the northern region and by heat flux from the ocean to the
ice along the southern ice edge, especially on the western side. A sea ice force balance
analysis shows that sea ice motion is largely associated with wind stress. The force due to
divergence of the internal ice stress tensor is large near the land boundaries in the north,
and it is small in the central and southern ice-covered region. During winter, which
dominates the annual mean, it is found that the simulated sea ice was mainly formed in
the northern Bering Sea, with the maximum ice growth rate occurring along the coast due
to cold air from northerly winds and ice motion away from the coast. South of St.
Lawrence Island, winds drive the model sea ice southwestward from the north to the
southwestern part of the ice-covered region. Along the ice edge in the western Bering
Sea, model sea ice is melted by warm ocean water, which is carried by the simulated
Bering Slope Current flowing to the northwest, resulting in the S-shaped asymmetric
pattern seen in the ice edge. In spring and fall, similar thermodynamic and dynamic
patterns occur in the model, but with typically smaller magnitudes and with season-specific
geographical and directional differences.
Reprint (pdf)