We're exploiting the propagation of sound in the ocean to build a navigation and communications system in the Arctic, so we can tell the vehicles where the ice boundary
is, whether they should go north or south, east or west.
24) In general, ice was always a danger for surface ships, even outside the pack--small floes could not be detected easily--so it was preferable to leave a margin of about forty miles from the ice boundary.
28) In April, when ice conditions were the worst, with the pack ice boundary at its southernmost, it might be necessary to route ships nearly a hundred miles farther south--leaving only about 150-200 miles to the Norwegian coast.
32) After April, the sea area gradually enlarged because the ice boundary moved north and east.
50) In May, Admiral Tovey advocated reducing the number of convoys during the coming months because improved weather conditions would greatly facilitate operations of the enemy's reconnaissance aircraft and bombers, and because the ice boundary would not have receded northward sufficiently to avoid these attacks.
116) This route ran more to the north than usual because the ice boundary had moved farther away from Bear Island.
With increasing thickness, longer and longer fetches are needed to break the ice, which results in the shifting of the landfast ice boundary further offshore during winter (see Fig.
On the geometry of the fast ice boundary in the Baltic Sea.