Modelling the freshwater balance and influence of icebergs in the Amundsen Sea, Antarctica
The Amundsen Sea has some of the highest thinning rates of ice shelves in Antarctica.
This imbalance is caused by changes in ocean melting, induced by warm Circumpolar
Deep Water (CDW) intrusions. The resulting changing freshwater balance could affect
the on-shelf currents and mixing. However, a clear understanding of the behaviour of
fresh water in the region is lacking. This thesis addresses that question. Firstly, an ide�alised model, with a passive ice shelf freshwater tracer, is used to show that the vertical
distribution of ice shelf meltwater changes with CDW layer thickness variation. This
model is used to determine the local freshwater feedback effect of ice shelf meltwater on
ice shelf melt rates. Secondly, a model of the Amundsen Sea is used, with passive freshwa�ter tracers, to investigate the relative magnitudes and spatial distributions of freshwater
components from different sources. In the surface and on a depth-average all freshwater
tracer concentrations are of comparable magnitude, though on a depth-average sea ice
and ice shelf meltwater are largest. The total freshwater tracer distribution is similar to
that of the ice-shelf meltwater tracer field. This implies a potential for ice-shelf meltwater
feedbacks, whereby abundant ice-shelf meltwater alters the ocean circulation and strat�ification, affecting melting. Thirdly, the effect of including grounded icebergs and their
freshwater flux are studied in detail. The presence of icebergs increases CDW intrusions
that reach the base of ice shelves. This suggests another possible feedback mechanism,
whereby more icebergs induce greater ice-shelf melting and hence more icebergs. How�ever, the strength of this potential feedback is dependent on poorly constrained sea-ice
model parameters