Antarctic subglacial lakes drain through sediment-floored canals: theory and model testing on real and idealized domains
Over the past decade, satellite observations of ice surface height have revealed that active subglacial lake systems are widespread under the Antarctic Ice Sheet, including the ice streams. For some of these systems, additional observations of ice-stream motion have shown that lake activity can affe...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-02-01
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| Series: | The Cryosphere |
| Online Access: | http://www.the-cryosphere.net/11/381/2017/tc-11-381-2017.pdf |
| _version_ | 1818351638780313600 |
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| author | S. P. Carter H. A. Fricker M. R. Siegfried |
| author_facet | S. P. Carter H. A. Fricker M. R. Siegfried |
| author_sort | S. P. Carter |
| collection | DOAJ |
| description | Over the past decade, satellite observations of ice surface height have
revealed that active subglacial lake systems are widespread under the
Antarctic Ice Sheet, including the ice streams. For some of these systems,
additional observations of ice-stream motion have shown that lake activity
can affect ice-stream dynamics. Despite all this new information, we still
have insufficient understanding of the lake-drainage process to incorporate
it into ice-sheet models. Process models for drainage of ice-dammed lakes
based on conventional <q>R-channels</q> incised into the base of the ice through
melting are unable to reproduce the timing and magnitude of drainage from
Antarctic subglacial lakes estimated from satellite altimetry given the low
hydraulic gradients along which such lakes drain. We have developed an
alternative process model, in which channels are mechanically eroded into the
underlying deformable subglacial sediment. When applied to the known active
lakes of the Whillans–Mercer ice-stream system, the model successfully
reproduced both the inferred magnitudes and recurrence intervals of lake-volume changes, derived from Ice, Cloud and land Elevation Satellite (ICESat)
laser altimeter data for the period 2003–2009. Water pressures in our model
changed as the flood evolved: during drainage, water pressures initially
increased as water flowed out of the lake primarily via a distributed system,
then decreased as the channelized system grew, establishing a pressure
gradient that drew water away from the distributed system. This evolution of
the drainage system can result in the observed internal variability of ice
flow over time. If we are correct that active subglacial lakes drain through
canals in the sediment, this mechanism also implies that active lakes are
typically located in regions underlain by thick subglacial sediment, which
may explain why they are not readily observed using radio-echo-sounding
techniques. |
| first_indexed | 2024-12-13T18:40:56Z |
| format | Article |
| id | doaj.art-c1c6a2835a264ecbb719ba35d06243dd |
| institution | Directory Open Access Journal |
| issn | 1994-0416 1994-0424 |
| language | English |
| last_indexed | 2024-12-13T18:40:56Z |
| publishDate | 2017-02-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | The Cryosphere |
| spelling | doaj.art-c1c6a2835a264ecbb719ba35d06243dd2022-12-21T23:35:14ZengCopernicus PublicationsThe Cryosphere1994-04161994-04242017-02-0111138140510.5194/tc-11-381-2017Antarctic subglacial lakes drain through sediment-floored canals: theory and model testing on real and idealized domainsS. P. Carter0H. A. Fricker1M. R. Siegfried2Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California, San Diego, CA, USAInstitute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California, San Diego, CA, USAInstitute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California, San Diego, CA, USAOver the past decade, satellite observations of ice surface height have revealed that active subglacial lake systems are widespread under the Antarctic Ice Sheet, including the ice streams. For some of these systems, additional observations of ice-stream motion have shown that lake activity can affect ice-stream dynamics. Despite all this new information, we still have insufficient understanding of the lake-drainage process to incorporate it into ice-sheet models. Process models for drainage of ice-dammed lakes based on conventional <q>R-channels</q> incised into the base of the ice through melting are unable to reproduce the timing and magnitude of drainage from Antarctic subglacial lakes estimated from satellite altimetry given the low hydraulic gradients along which such lakes drain. We have developed an alternative process model, in which channels are mechanically eroded into the underlying deformable subglacial sediment. When applied to the known active lakes of the Whillans–Mercer ice-stream system, the model successfully reproduced both the inferred magnitudes and recurrence intervals of lake-volume changes, derived from Ice, Cloud and land Elevation Satellite (ICESat) laser altimeter data for the period 2003–2009. Water pressures in our model changed as the flood evolved: during drainage, water pressures initially increased as water flowed out of the lake primarily via a distributed system, then decreased as the channelized system grew, establishing a pressure gradient that drew water away from the distributed system. This evolution of the drainage system can result in the observed internal variability of ice flow over time. If we are correct that active subglacial lakes drain through canals in the sediment, this mechanism also implies that active lakes are typically located in regions underlain by thick subglacial sediment, which may explain why they are not readily observed using radio-echo-sounding techniques.http://www.the-cryosphere.net/11/381/2017/tc-11-381-2017.pdf |
| spellingShingle | S. P. Carter H. A. Fricker M. R. Siegfried Antarctic subglacial lakes drain through sediment-floored canals: theory and model testing on real and idealized domains The Cryosphere |
| title | Antarctic subglacial lakes drain through sediment-floored canals: theory and model testing on real and idealized domains |
| title_full | Antarctic subglacial lakes drain through sediment-floored canals: theory and model testing on real and idealized domains |
| title_fullStr | Antarctic subglacial lakes drain through sediment-floored canals: theory and model testing on real and idealized domains |
| title_full_unstemmed | Antarctic subglacial lakes drain through sediment-floored canals: theory and model testing on real and idealized domains |
| title_short | Antarctic subglacial lakes drain through sediment-floored canals: theory and model testing on real and idealized domains |
| title_sort | antarctic subglacial lakes drain through sediment floored canals theory and model testing on real and idealized domains |
| url | http://www.the-cryosphere.net/11/381/2017/tc-11-381-2017.pdf |
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