Flow variability and ongoing margin shifts on Bindschadler a

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TitleFlow variability and ongoing margin shifts on Bindschadler and MacAyeal Ice Streams, West AntarcticaAbstractIce streams on the Ross Sea side of the West Antarctic Ice Sheet are known to experience flow variability on hourly, annual, and multicentury time scales. We report here on observations of flow variability at the decade scale on the Bindschadler and MacAyeal Ice Streams (BIS and MacIS). Our analysis makes use of archived ice velocity data and new mappings from composited Landsat 7 and Landsat 8 imagery that together span the interval from 1985 to 2014. Both ice streams speedup and slowdown in a range of about +-5 m a-2 over our various comparison intervals. The rates of change are variable in both time and space, and there is no evidence of external forcing at work across the two streams. Widespread changes are most likely linked to instability in the subglacial till and/or subglacial water flow. Sticky spots near the confluence of the two ice streams are loci for speed changes. These relatively young and slow-flowing features appear to be forcing shifts in margin position near the outlets of both streams. The margin jumps reduce the effective outlet widths of the streams by 20% and 30% on BIS and MacIS, respectively. Those magnitudes are similar to the outlet narrowing experienced by Kamb Ice Stream prior to its stagnation. Copyright 2016. American Geophysical Union. All Rights Reserved.AcknowledgementsThis work was supported by a New Zealand Antarctic Research Institute (NZARI RFP 2013-1) grant to Hulbe. The Landsat 4-, Landsat 5-, and SPOT-derived velocities were computed using IMCORR and are archived in the NSIDC VELMAP project. Newer Landsat scenes are archived at the USGS Earth- Explorer website, and the velocity mapping has been done by M. Klinger and T. Scambos at NSIDC using a Python-based software named PyCorr. We thank the Editor, Associate Editor, and three reviewers for careful reading and comments that helped us improve the clarity of our manuscript.

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1st AuthorHulbe, C.AuthorHulbe, C.Scambos, T.Klinger, M.Fahnestock, M.Year2016JournalJournal of Geophysical Research F: Earth SurfaceVolume121Number2Pages283-293DOI10.1002/2015JF003670URLhttps://www.scopus.com/inward/recor.....6aa3b1c1aebbf7cf084cc6eedKeywordsflow velocityice flowice marginice streamLandsatmappingtimescalewater flow, Antarctic Ice SheetAntarcticaBindschadler Ice StreamKamb Ice StreamMacAyeal Ice StreamRoss SeaSouthern OceanWest Antarctic Ice SheetWest Antarctica, rank4Author Keywordsice streamsshear marginssticky spots

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TypeArticleCitationHulbe, C., Scambos, T., Klinger, M. and Fahnestock, M. (2016). Flow variability and ongoing margin shifts on Bindschadler and MacAyeal Ice Streams, West Antarctica. Journal of Geophysical Research: Earth Surface, 121(2): 283-293