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

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.