Ice velocity of Jakobshavn Isbræ, Petermann Glacier, Nioghalvfjerdsfjorden, and Zachariæ Isstrøm, 2015–2017, from Sentinel 1-a/b SAR imagery
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Published:2018-06-18
Issue:6
Volume:12
Page:2087-2097
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ISSN:1994-0424
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Container-title:The Cryosphere
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language:en
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Short-container-title:The Cryosphere
Author:
Lemos AdrianoORCID, Shepherd Andrew, McMillan MalcolmORCID, Hogg Anna E., Hatton Emma, Joughin Ian
Abstract
Abstract. Systematically monitoring Greenland's outlet glaciers is central to
understanding the timescales over which their flow and sea level
contributions evolve. In this study we use data from the new Sentinel-1a/b
satellite constellation to generate 187 velocity maps, covering four key outlet
glaciers in Greenland: Jakobshavn Isbræ, Petermann Glacier,
Nioghalvfjerdsfjorden, and Zachariæ Isstrøm. These data provide a new
high temporal resolution record (6-day averaged solutions) of each glacier's
evolution since 2014, and resolve recent seasonal speedup periods and
inter-annual changes in Greenland outlet glacier speed with an estimated
certainty of 10 %. We find that since 2012, Jakobshavn Isbræ has been
decelerating, and now flows approximately 1250 m yr−1 (10 %), slower
than 5 years previously, thus reversing an increasing trend in ice velocity
that has persisted during the last decade. Despite this, we show that
seasonal variability in ice velocity remains significant: up to
750 m yr−1 (14 %) at a distance of 12 km inland of the terminus. We also
use our new dataset to estimate the duration of speedup periods (80–95 days)
and to demonstrate a strong relationship between ice front position and ice
flow at Jakobshavn Isbræ, with increases in speed of ∼ 1800 m yr−1
in response to 1 km of retreat. Elsewhere, we record significant
seasonal changes in flow of up to 25 % (2015) and 18 % (2016) at
Petermann Glacier and Zachariæ Isstrøm, respectively. This study
provides a first demonstration of the capacity of a new era of operational
radar satellites to provide frequent and timely monitoring of ice sheet
flow, and to better resolve the timescales over which glacier dynamics
evolve.
Funder
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Publisher
Copernicus GmbH
Subject
Earth-Surface Processes,Water Science and Technology
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