The influence of bathymetry over circulation on the Amundsen Sea
continental shelf
Abstract
Ice sheets such as Pine Island and Thwaites Glaciers which terminate at
their ice shelves in the eastern Amundsen Sea, West Antarctica, are
losing mass faster than most others about the continent. The mass loss
is due to basal melting, this affected by a deep current thought to be
guided by bottom bathymetry that transports warm Circumpolar Deep Water
(CDW) from the continental shelf break towards the ice shelves. This
current and associated heat transport are controlled by the near-surface
winds that vary on a range of timescales due to both anthropogenic and
natural effects. In this study we use idealised models to reproduce
essential features of the Amundsen Sea circulation and heat transport.
The aim is to elucidate the role of bathymetric features in shaping the
circulation and in enabling heat transport from the deep ocean onto the
continental shelf. Bathymetric variations along the continental slope
enhance on-shelf heat transport by inducing breaks in the Antarctic
Slope Front that separates off-shelf CDW from the colder, fresher shelf
waters. The idealised model results imply that a ridge that blocks deep
westward inflow from the Bellingshausen Sea leads to the existence of a
deep cyclonic circulation on the shelf. Part of this circulation is an
eastward undercurrent that flows along the continental shelf break. The
broader cyclonic circulation transports heat that has been recently
fluxed onto the shelf towards the south. These fundamental
investigations will help refine the aims of future fieldwork and
modelling.