Modelling the sources, variability and fate of freshwater in the Bellingshausen Sea, Antarctica

• Main Author: Regan, Heather
• Format: Thesis
• Language: English
• Published: 2017
• Subjects: Q Science (General); Antarctic; Antarctic Peninsula; Bellingshausen Sea; The Antarctic; Antarc*; Antarctica; Ice Shelf; Iceberg*; Sea ice
• Online Access: https://orca.cardiff.ac.uk/id/eprint/103393/; https://orca.cardiff.ac.uk/id/eprint/103393/1/FinalHRThesis_July_notrack.pdf; https://orca.cardiff.ac.uk/id/eprint/103393/2/Electronic%20Theses%20and%20Dissertations%20Publication%20Form.pdf

During the second half of the twentieth century, the Antarctic Peninsula exhibited a rapidincrease in air temperatures. This was accompanied by a reduction in sea ice extent,increased precipitation and a dramatic retreat of glaciers associated with an increase inheat flux from deep ocean water masses. Isotopic tracers have been used previously toinvestigate the relative importance of the different freshwater sources to the adjacentBellingshausen Sea, but the data coverage is strongly biased toward summer and unam-biguous determination of the different meteoric water contributions remains challenging.Here a high-resolution model is used to investigate the ocean’s response to the observedchanges in its different freshwater inputs (sea ice melt/freeze, precipitation/evaporation,iceberg melt, ice shelf melt and glacier melt). By developing the code to enable tracingof the sources and pathways of the individual components of the freshwater budget, it isshown that sea ice dominates the seasonal changes in freshwater content, but all sourcescontribute approximately equally to annual-mean freshwater fluxes and interannual fresh-water flux anomalies. Ice shelf melting is shown to be the largest contributor to freshwatercontent on the annual mean. Decadal trends in the salinity and stratification of the oceanare investigated, and a 20-year surface freshening trend is found to be predominantlydriven by decreasing autumn sea ice growth. By partitioning the freshwater in this way,insight is gained into the long-term freshwater balance and variability,and therefore the potential effects of a changing climate.