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| Titel |
Rapid increase in melt rates of Pine Island Glacier ice shelf during early stages of its retreat |
| VerfasserIn |
Jan De Rydt, Paul Holland, Pierre Dutrieux, Adrian Jenkins |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250080929
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| Zusammenfassung |
| Observations beneath the floating section of Pine Island Glacier have revealed the presence of
a subglacial ridge which rises up to 300m above the surrounding bathymetry. This
topographic feature has likely served as a steady grounding line position, and Pine Island
Glacier was at least partially grounded on the ridge until the early 1970s. Today the
grounding line is situated approximately 40km further upstream, following an ongoing phase
of rapid retreat. 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 melting of the ice shelf in the vicinity of the grounding line. In order to
understand how melt rates have changed during 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 gap between the ridge and the bottom of the ice
shelf strongly controls the inflow of warm bottom waters into the cavity, and hence
influences the melt rates. Model results provide evidence for rapidly increasing melt
rates at the onset of ice shelf thinning, but a weak change in melt rates once the
gap between the ridge and the ice shelf has passed a threshold value of -150m.
At present the gap is well over 150m, suggesting that observed variability in melt
rates is primarily controlled by other factors such as the depth of the thermocline. |
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