Modeling Ice-Crystal Fabric as a Proxy for Ice-Stream Stability
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Modeling Ice-Crystal Fabric as a Proxy for Ice-Stream Stability. / Lilien, David A.; Rathmann, Nicholas M.; Hvidberg, Christine S.; Dahl-Jensen, Dorthe.
I: Journal of Geophysical Research: Biogeosciences, Bind 126, Nr. 9, e2021JF006306, 21.09.2021.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Modeling Ice-Crystal Fabric as a Proxy for Ice-Stream Stability
AU - Lilien, David A.
AU - Rathmann, Nicholas M.
AU - Hvidberg, Christine S.
AU - Dahl-Jensen, Dorthe
PY - 2021/9/21
Y1 - 2021/9/21
N2 - The crystal structure within an ice sheet evolves in response to deformation; hence ice-crystal fabric records ice-flow history. However, the complexity of crystal-fabric evolution, and the lack of model results with which to compare data, limit the usefulness of fabric measurements, particularly in areas with complex ice dynamics. Here, we use an ice-flow model to identify characteristic fabrics associated with ice-stream onset, with the goal of aiding interpretation of fabric measurements. Using time-dependent model simulations, we identify how crystal fabric may be used to diagnose changes in an ice stream's speed or lateral position. Consistent with previous work, we find that fabric within an ice stream is generally a vertical girdle, though horizontal shear can lead to a horizontal single maximum. Transient simulations demonstrate that effects from changes in flow may be recorded in the crystal fabric for thousands of years after an ice stream activates and more than ten thousand years after an ice stream stagnates. Both transient and steady effects on fabric are sufficiently large as to be measurable in ice cores or with polarized radar, suggesting that in certain scenarios fabric could be used to identify past flow changes. These results could be used to design radar surveys in areas where ice streams are known to deactivate, such as the Siple Coast in Antarctica, or where they may migrate laterally or widen, such as in Northeast Greenland.
AB - The crystal structure within an ice sheet evolves in response to deformation; hence ice-crystal fabric records ice-flow history. However, the complexity of crystal-fabric evolution, and the lack of model results with which to compare data, limit the usefulness of fabric measurements, particularly in areas with complex ice dynamics. Here, we use an ice-flow model to identify characteristic fabrics associated with ice-stream onset, with the goal of aiding interpretation of fabric measurements. Using time-dependent model simulations, we identify how crystal fabric may be used to diagnose changes in an ice stream's speed or lateral position. Consistent with previous work, we find that fabric within an ice stream is generally a vertical girdle, though horizontal shear can lead to a horizontal single maximum. Transient simulations demonstrate that effects from changes in flow may be recorded in the crystal fabric for thousands of years after an ice stream activates and more than ten thousand years after an ice stream stagnates. Both transient and steady effects on fabric are sufficiently large as to be measurable in ice cores or with polarized radar, suggesting that in certain scenarios fabric could be used to identify past flow changes. These results could be used to design radar surveys in areas where ice streams are known to deactivate, such as the Siple Coast in Antarctica, or where they may migrate laterally or widen, such as in Northeast Greenland.
KW - ice-crystal fabric
KW - ice streams
KW - ice-flow history
KW - fabric modeling
KW - ice-flow modeling
KW - POLAR ICE
KW - WEST ANTARCTICA
KW - FLOW-LAW
KW - DYNAMIC RECRYSTALLIZATION
KW - POLYCRYSTALLINE ICE
KW - TEXTURE DEVELOPMENT
KW - ANISOTROPIC ICE
KW - SHEAR MARGINS
KW - SHEET
KW - CORE
U2 - 10.1029/2021JF006306
DO - 10.1029/2021JF006306
M3 - Journal article
VL - 126
JO - Journal of Geophysical Research: Solid Earth
JF - Journal of Geophysical Research: Solid Earth
SN - 0148-0227
IS - 9
M1 - e2021JF006306
ER -
ID: 281282469