Some remarks on the unusual Beaufort Sea ice conditions in summer 1975

Abstract

In the summer of 1975 the sea ice conditions between Point Barrow and Prudhoe Bay were the severest since 1898 when the ice did not move away from shore at all. In 1975 the movement started later than in any year since that time and was incomplete. From the meteorological point of view this event is very interesting and also had great economic ramifications because the need to resupply the Prudhoe Bay oil fields by barges could not be carried out as planned. These unusual ice conditions were caused by: a) a thicker than normal ice cover for the winter of 1974-75 owing to a cold and snow-deficient winter, b) a cooler than normal summer 1975 which not only slowed down the rate of ice decay but also shortened the period in which melting occurred, and c) the unusual wind conditions in summer 1975 which were caused by a persistent low pressure system over the high Canadian Arctic for July, August, and September, adding a northwesterly wind component to the average wind which kept the ice near to shore. This last reason is believed to be the most important.