Classifying Oceanographic Structures in the Amundsen Sea, Antarctica

Lars Boehme,Isabella Rosso

doi:10.1029/2020gl089412

Lars Boehme, Isabella Rosso

Open Access

https://doi.org/10.1029/2020gl089412

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Abstract

AbstractThe remote and often ice‐covered Amundsen Sea Embayment in Antarctica is important for transporting relatively warm modified Circumpolar Deep Water (mCDW) to the Western Antarctic Ice Sheet, potentially accelerating its thinning and contribution to sea level rise. To investigate potential pathways and variability of mCDW, 3809 CTD profiles (instrumented seal and ship‐based data) are classified using a machine learning approach (Profile Classification Model). Five vertical regimes are identified, and areas of larger variability highlighted. Three spatial regimes are captured: Off‐Shelf, Eastern and Central Troughs. The on‐shelf profiles further show a separation between cold and warm modes. The variability is higher north of Burke Island and at the southern end of the Eastern Trough, which reflects the convergence of different mCDW pathways between the Eastern and the Central Trough. Finally, a clear but variable clockwise circulation is identified in Pine Island Bay.

Highlights

The Amundsen Sea Embayment (ASE), Antarctica, defines the drainage area of the Western Antarctic Ice Sheet, which has been losing mass, contributing to sea level rise through the Pine Island and Thwaites Glaciers (Scambos et al, 2017)
The best spatial coverage is achieved in Pine Island Bay (PIB) and the southeastern part of the ASE in Cranton (∼74°S, 103°W) and Ferrero (∼73.5°S, 104°W) Bays
We showed that the PCM is a useful tool to analyze large datasets from shelf regions, enabling us to capture the pathways and variability of the modified Circumpolar Deep Water (mCDW) in the ASE

Summary

Introduction

The Amundsen Sea Embayment (ASE), Antarctica, defines the drainage area of the Western Antarctic Ice Sheet, which has been losing mass, contributing to sea level rise through the Pine Island and Thwaites Glaciers (Scambos et al, 2017) These glaciers rest mainly on land that lies below sea level and often deepens toward the interior of the ice sheet, which together with increased mass loss, could lead to marine ice sheet instability and its eventual collapse (Alley et al, 2015) potentially rising sea level by up to 2.5 m within 500 years (Bamber et al, 2009; DeConto & Pollard, 2016). The variability of the water mass structure in PIB can be driven by both

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