AIDJEX Bulletin #40 - Polar Science Center - University of Washington

the barges managed to reach their destination by breaking through ice as much
as a foot thick. Others turned back and their cargoes were eventually shipped
overland to Prudhoe Bay. The following year, despite long-term predictions
that ice conditions during late spring and early summer would be even worse
than before, tugs were able to get the barges through easily.
It is possible that the main reason for this surprising turn of events
was the development of a new ice-breaking barge, the Arctic ChaZZenger, which
allows commercial vessels for the first time to operate within rather than
around the ice pack. Indeed, one might surmise that the ability to build
such icebreakers will eliminate the need for ice forecasting in shipping
plans. However, in fact this advance in technology increases the ne.ed for
an accurate ice forecasting system. The apparent contradiction arises because
no ship--not even the Soviet icebreaker Arktika, which sailed to the North
Pole in December 1977--is capable of sailing on a chosen course at a chosen
speed under arbitrarily heavy ice conditions. Therefore, the prediction of
times and locations of heavy ice conditions and high ice pressure becomes
especially useful to ships operating within the ice pack.
Shipping is not the only justification for improved ice forecasting techniques
in the Arctic. Oil-producing wells will soon be a reality in the
shallow coastal shelf off the North Slope, an area which is exposed to active
ice motion. If oil workers know in advance what the ice is going to do, they
can take certain precautions (cap a well or move the platform to a safer site,
for example) to prevent a disastrous oil spill or the loss of equipment and
lives.
On the time and space scales that we are addressing, ice motion and
behavior are controlled primarily by the winds and, to a lesser extent, by
the ocean currents. If these quantities can be forecast, then ice motion
and state may be forecast by the same simulation technique as was developed
during AIDJEX to study sea ice response (Coon et al., 1974). Although the
primary region of interest to AIDJEX is the central Beaufort Sea, it has been
shown (Pritchard and Schwaegler, 1975; Coon et al., 1977; Pritchard et al., 1977)
that the AIDJEX model can simulate motion and state in the nearshore regions as well.
The work by Coon et al. (1977) attempts to interpret the results of the
simulation of ice dynamics during spring 1975 in terms useful in a forecasting
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