Iceberg calving of Thwaites Glacier, West Antarctica: full-Stokes modeling combined with linear elastic fracture mechanics
Thwaites Glacier (TG), West Antarctica, has been losing mass and retreating rapidly in the past few decades. Here, we present a study of its calving dynamics combining a two-dimensional flow-band full-Stokes (FS) model of its viscous flow with linear elastic fracture mechanics (LEFM) theory to mo...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-05-01
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| Series: | The Cryosphere |
| Online Access: | http://www.the-cryosphere.net/11/1283/2017/tc-11-1283-2017.pdf |
| Summary: | Thwaites Glacier (TG), West Antarctica, has been losing mass and retreating
rapidly in the past few decades. Here, we present a study of its calving
dynamics combining a two-dimensional flow-band full-Stokes (FS) model of its
viscous flow with linear elastic fracture mechanics (LEFM) theory to model
crevasse propagation and ice fracturing. We compare the results with those
obtained with the higher-order (HO) and the shallow-shelf approximation (SSA)
models coupled with LEFM. We find that FS/LEFM produces surface and bottom
crevasses that are consistent with the distribution of depth and width of
surface and bottom crevasses observed by NASA's Operation IceBridge radar
depth sounder and laser altimeter, whereas HO/LEFM and SSA/LEFM do not
generate crevasses that are consistent with observations. We attribute the
difference to the nonhydrostatic condition of ice near the grounding line,
which facilitates crevasse formation and is accounted for by the FS model but
not by the HO or SSA models. We find that calving is enhanced when
pre-existing surface crevasses are present, when the ice shelf is shortened
or when the ice shelf front is undercut. The role of undercutting depends on
the timescale of calving events. It is more prominent for glaciers with rapid
calving rates than for glaciers with slow calving rates. Glaciers extending
into a shorter ice shelf are more vulnerable to calving than glaciers
developing a long ice shelf, especially as the ice front retreats close to
the grounding line region, which leads to a positive feedback to calving
events. We conclude that the FS/LEFM combination yields substantial
improvements in capturing the stress field near the grounding line of a
glacier for constraining crevasse formation and iceberg calving. |
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| ISSN: | 1994-0416 1994-0424 |