Geoscience Reference
In-Depth Information
7
Arctic Ocean-Sea Ice-Climate Interactions
Overview
The mean seasonal variation of sea ice extent was reviewed in
Chapter 2
along with some basic aspects of sea ice circulation, morphology the
factors contributing to sea ice growth. As introduced there, the existence
of the ice cover is not simply a function of low winter temperatures;
its formation and persistence is fostered by the existence of a relatively
fresh surface layer, maintained by river runoff, the import of low-
salinity water through the Bering Strait, net precipitation over the Arctic
Ocean, and the distillation process associated with ice formation itself.
Seasonally, summer melt of the fairly fresh ice is also important. The
characteristics of river runoff were examined in
Chapter 6
. In
Chapter 3
,
we discussed the role that sea ice plays in the Arctic's atmospheric
energy budget, with sea ice melt maintaining a downward net surface
flux (from the atmosphere to the ocean) in summer, and sea ice growth
adding heat to the atmosphere in winter.
Chapter 5
shed further light on
this issue through a review of surface energy exchanges. In
Chapter 4
,
we documented sea ice impacts on regional aspects of the atmospheric
circulation through enhanced baroclinicity along the ice margins, and
how the atmospheric circulation many now be responding to observed
reductions in ice extent. The present chapter extends our understanding of
sea ice and its interactions with the atmosphere and ocean.
The growth of sea ice up to about 1 m in thickness can be approximated
in terms of freezing degree days. This is because the temperature
gradient in thin ice is essentially linear. By contrast, the growth of
thicker ice, primarily multiyear ice, which has historically attained
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