Geoscience Reference
In-Depth Information
Figure 7.12.
Mean pattern of sea ice drift in the Arctic for summer, based primarily on
data from the IABP, the North Pole program and other sources with overlay of sea level
pressure from NCEP/NCAR (ice drift field courtesy of I. Rigor, Polar Science Center,
University of Washington, Seattle, WA, sea level pressure field by the authors).
thickness CDFs such as shown in
Plate 11
. Thick deformed FYI is in turn more
likely to survive a summer melt season to become MYI than is undeformed FYI.
The large ice thicknesses north of the Canadian Arctic Archipelago are associated
with ridging and rafting. The basic idea is that the sea ice accommodates diver-
gence by increasing the area of open water rather than thinning. It accommodates
convergent motion by reducing the area of open water and by rafting and ridging
(Thorndike,
1986
).
A standard data product from the IABP is ice velocity derivatives, from which
divergence and shear (which together represent to total deformation) can be calcu-
lated along with vorticity (the rotational part of the flow). Similar products can be
made from satellite-derived ice motion fields. Care must be exercised in interpreting
such data because the true ice motion field is granular, with velocity discontinuities
