Evolving ice fronts and surface speeds in the Amundsen Sea Embayment between 1972-2010
Abstract
Thwaites and Pine Island Glaciers are among the largest, fastest flowing, and fastest thinning glaciers in Antarctica. Their ice fronts have also migrated significantly during the past few decades, although the relationship between their ice-front variability and other dynamic changes is poorly known. Here we present a history of the ice-front position in the Amundsen Sea Embayment for 1972-2010 between Bear Peninsula and the nunataks north of Pine Island Glacier. The ice-front position is derived from local mosaics of Landsat 1-7, MODIS and QuickBird imagery. Ice-front histories along the central flowlines of the largest glaciers in this embayment (Thwaites, Pine Island and Smith) resemble a sawtooth pattern superimposed upon a smaller trend of approximately linear retreat. Pine Island Glacier’s ice-front position varied the least (~ 15 km) during this period, while Thwaites Glacier’s varied the most (~ 80 km). The largest calving events for Pine Island and Thwaites Glaciers occurred in 2001-2002 and 2002-2003, respectively; the latter event is associated with the detachment of the Thwaites ice tongue. The similar timing of these events suggests that, as for the dynamic thinning of coastal grounded ice, regional oceanographic forcing is an important underlying cause. We also compare the ice-front history of Thwaites Glacier to a new compilation of its surface-speed history. Its ice tongue accelerated ~ 1 km/yr between 1972-2000; this acceleration increased modestly as its ice front advanced, beginning in the late 1980’s, after its iceberg tongue detached. The response of the grounded ice immediately upstream of the grounding line to these changes appears muted, supporting predictions of minimal buttressing by Thwaites Glacier’s floating ice. However the period of overlap between measurements of surface velocity across both the floating and grounded ice is less than a decade. Our new ice-front history of the Amundsen Sea Embayment and surface-speed history of Thwaites Glacier offer a longer-term perspective with which to compare the recent rapid changes observed in this region.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFM.C11A0531M
- Keywords:
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- 0728 CRYOSPHERE / Ice shelves;
- 0730 CRYOSPHERE / Ice streams;
- 0758 CRYOSPHERE / Remote sensing;
- 0774 CRYOSPHERE / Dynamics