Ocean Circulation and Ice Shelf Melting in the Bellingshausen Sea

Abstract

The West Antarctic Ice Sheet is currently losing mass, and ocean-driven basal melting of ice shelves is a key driver of net mass loss. A modified version of warm Circumpolar Deep Water (mCDW) is present on the continental shelf in the Bellingshausen Sea, leading to high ice shelf basal melt rates. This thesis presents data from a detailed oceanographic survey of the Bellingshausen Sea, with the aim of characterising the physical oceanography of the region and assessing how the oceanographic regime influences the ice shelves. This includes analysing the flow of Circumpolar Deep Water across the shelf break, assessing ocean circulation and water properties on the continental shelf, and quantifying ice shelf basal melt rates.
Data show that the Antarctic Circumpolar Current is a primary circulation feature along the continental slope, and the source of mCDW that flows onto the continental shelf. Analyses reveal spatial differences in shelf break processes, resulting in differences in mCDW properties across the shelf sea. Warmer mCDW was present in the east, due to eddies transporting warmer Upper Circumpolar Deep Water across the shelf break. Cooler mCDW in the west is related to bathymetric steering of the Antarctic Circumpolar Current away from the shelf break, and uplift of cooler Lower Circumpolar Deep Water that can access the continental shelf. In addition to cooler mCDW, a deeper thermocline and colder Winter Water layer was seen in the west. Analyses indicate that this cooler water sourced from the west drives most of the ice shelf melting, which could have important implications for basal melt rates. Calculations of basal melt rates indicate that ice shelves were melting close to equilibrium at the time of the cruise. Data revealed that glacial meltwater is transported in a westward flowing coastal current and is exported out of the region, where it can potentially exert an influence outside of the Bellingshausen Sea.

Date of Award	19 Feb 2026
Original language	English
Awarding Institution	Northumbria University
Supervisor	Adrian Jenkins (Supervisor), Jan De Rydt (Supervisor), Miguel Angel Morales Maqueda (Supervisor) & Paul R. Holland (Supervisor)