GFI/BCCR Seminar: Influences of tides, heat, and circulation on the melting of Filchner-Ronne Ice Shelf, Weddell Sea, Antarctica.
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Rachael Mueller (Earth & Space Research, Aqvaplan-Niva)
Influences of tides, heat, and circulation on the melting of Filchner-Ronne Ice Shelf, Weddell Sea, Antarctica.
Abstract
Recent modeling studies of ocean circulation in the southern Weddell Sea, Antarctica, show an increase over this century of ocean heat influx into the cavity beneath Filchner-Ronne Ice Shelf (FRIS). This increase in ocean heat would lead to more basal melting and a modification of the FRIS ice draft. The corresponding change in cavity shape will affect the spatial distribution of tidal current speeds, which play important roles in basal melting under FRIS. This feedback between heat flux, basal melting, and tides will affect the evolution of FRIS under the influence of a changing climate. We explore the impact of these feedbacks with a three-dimensional ocean model of the southern Weddell Sea that is forced by (1) thermodynamic exchange beneath the ice shelf and (2) tides along the open boundaries. Our results show regionally-dependent feedbacks that, in some areas, substantially modify the melt rates near the grounding lines of buttressed ice streams that flow into FRIS. These feedbacks are introduced by variations in meltwater production as well as the circulation of this meltwater within the cavity; they are influenced locally by sensitivity of tidal currents to water column thickness and non-locally by changes in circulation pathways that transport an integrated history of mixing and meltwater entrainment along flow paths. This presentation highlights the influence of tides on affecting the response of FRIS to a changing climate, with a special emphasis on regional variations and feedbacks.