The effect of possible Taylor columns on the summer ice retreat in the Chukchi Sea

Abstract

The Chukchi Sea topography consists of a broad, flat, 50-m-deep plain, with two prominent shoals, Herald and Hanna, which have horizontal dimensions of about 100 km and rise to depths of about 30 m. Herald Shoal in particular is a prominent, isolated seamount which, because of the warm water flux in summer through Bering Strait, has a warm 0.1 m s-1 flow incident upon it. Examination of active and passive microwave imagery of the region for 1992-1994 shows that as the general ice cover recedes, the ice remains preferentially over Herald Shoal for 3-4 weeks after the surrounding ice has melted. A scale analysis suggests that the cause of the ice persistence is the formation of a Taylor column over the shoal, which traps cold water and ice above it. A similar trapping of ice occurs over Hanna Shoal and on its eastern slope, but the response is complicated by a very different topography and the northward flow down Barrow Canyon.