Water mass properties in the Amundsen Sea, Antarctica, using seal-borne tags

• Main Author: Mallett, Helen
• Format: Thesis
• Language: English
• Published: 2019
• Subjects: Antarctic; Amundsen Sea; West Antarctic Ice Sheet; Antarc*; Antarctica; Ice Sheet; Ice Shelf
• Online Access: https://ueaeprints.uea.ac.uk/id/eprint/72628/; https://ueaeprints.uea.ac.uk/id/eprint/72628/1/thesis.pdf

Global attention is focused on the melting of the West Antarctic Ice Sheet and the impacts of associated sea level rise. Glaciers in the Amundsen Sea Embayment are some of the biggest contributors, yet difficulty collecting data in this area, especially during winter when harsh weather and ice cover prevent many traditional observation techniques, means detailed understanding of the relevant processes is limited. This thesis presents a dataset of >11,000 new seal-borne hydrographic profiles from the summer, autumn and winter seasons of 2014, enabling seasonal comparisons of deep water, and for the first time, the upper ocean. A through evaluation of the quality of the seal tag dataset is presented, along with details of the appropriate corrections. The magnitude of corrections derived from pre-deployment tests suggest that some tag datasets lacking these pre-deployment tests might not meet the stated accuracies. One of the drivers of increased glacial melt in this region is warm Circumpolar Deep Water (CDW) increasingly crossing the continental shelf, and contributing to increased ice mass loss. Seasonal analysis reveals a CDW layer on average 49 db thicker in late winter (August to October) than in late summer (February to April), the reverse seasonality of that seen at moorings in the western trough. This layer contains more heat in winter. In the upper ocean, salinification, cooling and the deepening of the mixed layer begins in or before February, and continues until June/July. The distance to which mooring-top observations can be extrapolated upward into the upper ocean is examined, and found to be between 110 and 230 m, although dependent on local conditions and the depth of the mooring. These observations form a crucial building block for future study on seasonality and variability in the area, and are essential for verifying model simulations of ice shelf melt.