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Impact of external factors on changing dynamics of Mertz Glacier Tongue prior to 2010 calving

Impact of external factors on changing dynamics of Mertz Glacier Tongue prior to 2010 calving
Robert A. Massom

Authors

Robert A. Massom
Australian Antarctic Division, Channel Highway, Kingston, Tasmania 7053, Australia
and Antarctic Climate & Ecosystems Cooperative Research Centre, University of Tasmania, Private Bag 80, Hobart, Tasmania 7001, Australia

A. Barry Giles
Antarctic Climate & Ecosystems Cooperative Research Centre, University of Tasmania, Private Bag 80, Hobart, Tasmania 7001, Australia

Roland C Warner
Australian Antarctic Division, Channel Highway, Kingston, Tasmania 7053, Australia
and Antarctic Climate & Ecosystems Cooperative Research Centre, University of Tasmania, Private Bag 80, Hobart, Tasmania 7001, Australia

Benoit Legrésy
LEGOS (CNRS-CNES-UPS-IRD), Av. E. Belin, 31400 Toulouse, France

Helen A. Fricker
Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093-0225, USA

Glenn Hyland
Australian Antarctic Division, Channel Highway, Kingston, Tasmania 7053, Australia
and Antarctic Climate & Ecosystems Cooperative Research Centre, University of Tasmania, Private Bag 80, Hobart, Tasmania 7001, Australia

Lydie Lescarmontier
LEGOS (CNRS-CNES-UPS-IRD), Av. E. Belin, 31400 Toulouse, France.
Now at: Research School of Earth Sciences, Australian National University, Building 142 Mills Road, Acton, ACT 0200, Australia

Neal Young
Antarctic Climate & Ecosystems Cooperative Research Centre, University of Tasmania, Private Bag 80, Hobart, Tasmania 7001, Australia

Abstract

Iceberg calving accounts for about half the mass lost from Antarctica, yet our current understanding of the process is inadequate. The Mertz Glacier tongue (MGT) in East Antarctica experienced a large calving event in 2010, producing iceberg C28. Satellite observations over the preceding decade provide an opportunity to analyse the behaviour of the MGT prior to the calving. Major and occasionally abrupt changes in flow dynamics occurred in response to several “external” factors. These factors include apparent contact of the northwestern tip of the MGT with the seabed beginning in 2002, which caused the MGT flow direction to rotate rapidly by approximately 46° eastwards. This was immediately followed by a rapid opening of the western part of a major transverse rift ~70 km to the south; which became the C28 calving front. A more localized external factor was an abrupt collision of vast iceberg C08 (calved from the Ninnis Glacier tongue in 1980-82) with the northeastern flank of the MGT. This temporarily knocked the northern portion of the MGT a few hundred metres to the west before it “rebounded” to approximately its original flow direction. Finally, a small iceberg, grounding near the northwestern tip of the MGT, “chiselled” off numerous small icebergs as the tongue advanced, removing 36.4 km2 of ice over five-years. We propose that detailed understanding of case-specific external factors may be critical to understanding how glacier tongues calve, and this might considerably complicate modeling efforts to predict the ice sheet contribution to sea level change.

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This page was last modified on 23 September 2013.