Initial results from geophysical surveys and shallow coring of the Northeast Greenland Ice Stream (NEGIS)

The Northeast Greenland Ice Stream (NEGIS) is the sole interior Greenlandicice stream. Fast flow initiates near the summit dome, and the ice streamterminates approximately 1000 km downstream in three large outlet glaciersthat calve into the Greenland Sea. To better understand this importantsystem, i...

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Bibliographic Details
Published in:The Cryosphere
Main Authors: Vallelonga, P, Christianson, K, Alley, RB, Anandakrishnan, JEM, Dahl-Jensen, D, Gkenis, V, Holme, C, Jacobel, RW, Karlsson, NB, Keisling, BA, Kipfstuhl, S, Kjaer, HA, Kristensen, MEL, Muto, A, Peters, LE, Popp, T, Riverman, KL, Svensson, AM, Tibuleac, C, Vinther, BM, Weng, Y, Winstrup, M
Format: Article in Journal/Newspaper
Language:English
Published: Copernicus GmbH 2014
Subjects:
Earth Sciences
Physical Geography and Environmental Geoscience
Glaciology
Greenland
Greenland ice core
Greenland Ice core Project
Greenland Sea
ice core
Ice Sheet
NGRIP
North Greenland
North Greenland Ice Core Project
The Cryosphere
Online Access:https://doi.org/10.5194/tc-8-1275-2014
http://ecite.utas.edu.au/103752
Description
Summary:The Northeast Greenland Ice Stream (NEGIS) is the sole interior Greenlandicice stream. Fast flow initiates near the summit dome, and the ice streamterminates approximately 1000 km downstream in three large outlet glaciersthat calve into the Greenland Sea. To better understand this importantsystem, in the summer of 2012 we drilled a 67 m firn core and conductedground-based radio-echo sounding (RES) and active-source seismic surveys ata site approximately 150 km downstream from the onset of streaming flow(NEGIS firn core, 7537.61' N, 3556.49' W).The site is representative of the upper part of the ice stream, whilealso being in a crevasse-free area for safe surface operations. Annual cycles were observed for insoluble dust, sodium and ammoniumconcentrations and for electrolytic conductivity, allowing a seasonallyresolved chronology covering the past 400 yr. Annual layer thicknessesaveraged 0.11 m ice equivalent (i.e.) for the period 16072011, althoughaccumulation varied between 0.08 and 0.14 m i.e., likely due to flow-relatedchanges in surface topography. Tracing of RES layers from the NGRIP (North Greenland Ice Core Project) ice coresite shows that the ice at NEGIS preserves a climatic record of at least thepast 51 kyr. We demonstrate that deep ice core drilling in this locationcan provide a reliable Holocene and late-glacial climate record, as well ashelping to constrain the past dynamics and icelithosphere interactions ofthe Greenland Ice Sheet.

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