Geometric and oceanographic controls on melting beneath Pine Island Glacier

de Rydt, Jan, Holland, Paul, Dutrieux, P. and Jenkins, Adrian (2014) Geometric and oceanographic controls on melting beneath Pine Island Glacier. Journal of Geophysical Research: Oceans, 119 (4). pp. 2420-2438. ISSN 2169-9275

Full text not available from this repository.
Official URL: http://dx.doi.org/10.1002/2013JC009513

Abstract

Observations beneath the floating section of Pine Island Glacier have revealed the presence of a subglacial ridge which rises up to 300 m above the surrounding bathymetry. This topographic feature probably served as a steady grounding line position until sometime before the 1970s, when an ongoing phase of rapid grounding line retreat was initiated. As a result, a large ocean cavity has formed behind the ridge, strongly controlling the ocean circulation beneath the ice shelf and modulating the ocean water properties that cause ice melting in the vicinity of the grounding line. In order to understand how melt rates have changed during the various phases of cavity formation, we use a high‐resolution ocean model to simulate the cavity circulation for a series of synthetic geometries. We show that the height of the ridge and the gap between the ridge and ice shelf strongly control the inflow of warm bottom waters into the cavity, and hence the melt rates. Model results suggest a rapid geometrically controlled increase of meltwater production at the onset of ice thinning, but a weak sensitivity to geometry once the gap between the ridge and ice shelf has passed a threshold value of about 200 m. This provides evidence for a new, coupled, ice‐ocean feedback acting to enhance the initial retreat of an ice stream from a bedrock high. The present gap is over 200 m, and our results suggest that observed variability in melt rates is now controlled by other factors, such as the depth of the thermocline.

Item Type: Article
Uncontrolled Keywords: Pine Island Glacier, melt rates, ice‐ocean interaction
Subjects: F800 Physical and Terrestrial Geographical and Environmental Sciences
Department: Faculties > Engineering and Environment > Geography and Environmental Sciences
Depositing User: Becky Skoyles
Date Deposited: 03 Jul 2018 14:16
Last Modified: 10 Oct 2019 21:03
URI: http://nrl.northumbria.ac.uk/id/eprint/34802

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