Modelling Circumpolar Deep Water intrusions on the Amundsen Sea continental shelf, Antarctica

TLDR

The model shows that warm Circumpolar Deep Water reaches the inner shelf through a submarine trough and that seasonal and decadal variations in on‑shelf flow are driven by changes in wind patterns associated with the Amundsen Sea Low. The model finds that CDW influx variability, linked to wind forcing, coincides with a warming period that aligns with observed thinning and acceleration of Pine Island Glacier.

Abstract

Results are presented from an isopycnic coordinate model of ocean circulation in the Amundsen Sea, focusing on the delivery of Circumpolar Deep Water (CDW) to the inner continental shelf around Pine Island Bay. The warmest waters to reach this region are channeled through a submarine trough, accessed via bathymetric irregularities along the shelf break. Temporal variability in the influx of CDW is related to regional wind forcing. Easterly winds over the shelf edge change to westerlies when the Amundsen Sea Low migrates west and south in winter/spring. This drives seasonal on‐shelf flow, while inter‐annual changes in the wind forcing lead to inflow variability on a decadal timescale. A modelled period of warming following low CDW influx in the late 1980's and early 1990's coincides with a period of observed thinning and acceleration of Pine Island Glacier.