Crystal orientation fabric anisotropy causes directional hardening of the Northeast Greenland Ice Stream

Tamara Annina Gerber*, David A. Lilien, Nicholas Mossor Rathmann, Steven Franke, Tun Jan Young, Fernando Valero-Delgado, M. Reza Ershadi, Reinhard Drews, Ole Zeising, Angelika Humbert, Nicolas Stoll, Ilka Weikusat, Aslak Grinsted, Christine Schøtt Hvidberg, Daniela Jansen, Heinrich Miller, Veit Helm, Daniel Steinhage, Charles O’Neill, John PadenSiva Prasad Gogineni, Dorthe Dahl-Jensen, Olaf Eisen

*Corresponding author af dette arbejde

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

11 Citationer (Scopus)
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Abstract

The dynamic mass loss of ice sheets constitutes one of the biggest uncertainties in projections of ice-sheet evolution. One central, understudied aspect of ice flow is how the bulk orientation of the crystal orientation fabric translates to the mechanical anisotropy of ice. Here we show the spatial distribution of the depth-averaged horizontal anisotropy and corresponding directional flow-enhancement factors covering a large area of the Northeast Greenland Ice Stream onset. Our results are based on airborne and ground-based radar surveys, ice-core observations, and numerical ice-flow modelling. They show a strong spatial variability of the horizontal anisotropy and a rapid crystal reorganisation on the order of hundreds of years coinciding with the ice-stream geometry. Compared to isotropic ice, parts of the ice stream are found to be more than one order of magnitude harder for along-flow extension/compression while the shear margins are potentially softened by a factor of two for horizontal-shear deformation.

OriginalsprogEngelsk
Artikelnummer2653
TidsskriftNature Communications
Vol/bind14
Udgave nummer1
Antal sider12
ISSN2041-1723
DOI
StatusUdgivet - 8 maj 2023

Bibliografisk note

Funding Information:
This research was undertaken, in part, thanks to funding from the Canada Excellence Research Chairs Programme and has been financially supported by the Villum Investigator Project IceFlow (Grant No. 16572 to D.D.-J.). Radar development was further supported by funding from the University of Alabama. EGRIP is directed and organised by the Centre for Ice and Climate at the Niels Bohr Institute, University of Copenhagen. It is supported by funding agencies and institutions in Denmark (A. P. Møller Foundation, University of Copenhagen), the USA (US National Science Foundation, Office of Polar Programmes), Germany (Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research), Japan (National Institute of Polar Research and Arctic Challenge for Sustainability), Norway (the University of Bergen and Trond Mohn Foundation), Switzerland (Swiss National Science Foundation), France (French Polar Institute Paul-Émile Victor, Institute for Geosciences and Environmental Research), Canada (University of Manitoba), and China (Chinese Academy of Sciences and Beijing Normal University). S.F. received funding from the German Academic Exchange Service (DAAD): Forschungsstipendien für promovierte Nachwuchswissenschaftlerinnen und -wissenschaftler. M.R.E. was supported by a DFG Emmy Noether grant (grant no. DR 822/3-1). The authors would like to thank the EGRIP logistic support and field personnel, the US Air National Guard flights provided by the US National Science Foundation as well as Ken Borek aircraft crew.

Funding Information:
This research was undertaken, in part, thanks to funding from the Canada Excellence Research Chairs Programme and has been financially supported by the Villum Investigator Project IceFlow (Grant No. 16572 to D.D.-J.). Radar development was further supported by funding from the University of Alabama. EGRIP is directed and organised by the Centre for Ice and Climate at the Niels Bohr Institute, University of Copenhagen. It is supported by funding agencies and institutions in Denmark (A. P. Møller Foundation, University of Copenhagen), the USA (US National Science Foundation, Office of Polar Programmes), Germany (Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research), Japan (National Institute of Polar Research and Arctic Challenge for Sustainability), Norway (the University of Bergen and Trond Mohn Foundation), Switzerland (Swiss National Science Foundation), France (French Polar Institute Paul-Émile Victor, Institute for Geosciences and Environmental Research), Canada (University of Manitoba), and China (Chinese Academy of Sciences and Beijing Normal University). S.F. received funding from the German Academic Exchange Service (DAAD): Forschungsstipendien für promovierte Nachwuchswissenschaftlerinnen und -wissenschaftler. M.R.E. was supported by a DFG Emmy Noether grant (grant no. DR 822/3-1). The authors would like to thank the EGRIP logistic support and field personnel, the US Air National Guard flights provided by the US National Science Foundation as well as Ken Borek aircraft crew.

Publisher Copyright:
© 2023, The Author(s).

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