Sub-seasonal thaw slump mass wasting is not consistently energy limited at the landscape scale
Predicting future thaw slump activity requires a sound understanding of the atmospheric drivers and geomorphic controls on mass wasting across a range of timescales. On sub-seasonal timescales, sparse measurements indicate that mass wasting at active slumps is often limited by the energy availabl...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-02-01
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| Series: | The Cryosphere |
| Online Access: | https://www.the-cryosphere.net/12/549/2018/tc-12-549-2018.pdf |
| Summary: | Predicting future thaw slump activity requires a sound understanding of the
atmospheric drivers and geomorphic controls on mass wasting across a range of
timescales. On sub-seasonal timescales, sparse measurements indicate that
mass wasting at active slumps is often limited by the energy available for
melting ground ice, but other factors such as rainfall or the formation of an
insulating veneer may also be relevant. To study the sub-seasonal drivers, we
derive topographic changes from single-pass radar interferometric data
acquired by the TanDEM-X satellites. The estimated elevation changes at 12 m
resolution complement the commonly observed planimetric retreat rates by
providing information on volume losses. Their high vertical precision (around
30 cm), frequent observations (11 days) and large coverage (5000 km<sup>2</sup>)
allow us to track mass wasting as drivers such as the available energy change
during the summer of 2015 in two study regions. We find that thaw slumps in
the Tuktoyaktuk coastlands, Canada, are not energy limited in June, as they
undergo limited mass wasting (height loss of around
0 cm day<sup>−1</sup>) despite the ample available
energy, suggesting the widespread presence of early season insulating snow or
debris veneer. Later in summer, height losses generally increase (around
3 cm day<sup>−1</sup>), but they do so in distinct ways. For many slumps, mass
wasting tracks the available energy, a temporal pattern that is also observed
at coastal yedoma cliffs on the Bykovsky Peninsula, Russia. However, the
other two common temporal trajectories are asynchronous with the available
energy, as they track strong precipitation events or show a sudden speed-up
in late August respectively. The observed temporal patterns are poorly
related to slump characteristics like the headwall height. The contrasting
temporal behaviour of nearby thaw slumps highlights the importance of complex
local and temporally varying controls on mass wasting. |
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| ISSN: | 1994-0416 1994-0424 |