UA cloudflare authentication

Department of Geological Sciences

Permanent URI for this community

https://ir.ua.edu/handle/123456789/54

Browse

Browsing Department of Geological Sciences by Author "Alfred Wegener Institute, Helmholtz Centre for Polar & Marine Research"

Now showing 1 - 1 of 1
  • Thumbnail Image
    Item
    Crystal orientation fabric anisotropy causes directional hardening of the Northeast Greenland Ice Stream
    (Nature Portfolio, 2023) Gerber, Tamara Annina; Lilien, David A.; Rathmann, Nicholas Mossor; Franke, Steven; Young, Tun Jan; Valero-Delgado, Fernando; Ershadi, M. Reza; Drews, Reinhard; Zeising, Ole; Humbert, Angelika; Stoll, Nicolas; Weikusat, Ilka; Grinsted, Aslak; Hvidberg, Christine Schott; Jansen, Daniela; Miller, Heinrich; Helm, Veit; Steinhage, Daniel; O'Neill, Charles; Paden, John; Gogineni, Siva Prasad; Dahl-Jensen, Dorthe; Eisen, Olaf; University of Copenhagen; Niels Bohr Institute; University of Manitoba; Helmholtz Association; Alfred Wegener Institute, Helmholtz Centre for Polar & Marine Research; University of Cambridge; University of St Andrews; Eberhard Karls University of Tubingen; University of Bremen; University of Kansas; University of Alabama Tuscaloosa
    This study uses radio-echo sounding measurements, ice-core data and models to map the spatial variation in ice-crystal orientation in the northeast Greenland Ice Stream and shows how it potentially affects the ice-flow dynamics in this region. 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.