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| Titel |
Sensitivity of airborne geophysical data to sublacustrine and near-surface permafrost thaw |
| VerfasserIn |
B. J. Minsley, T. P. Wellman, M. A. Walvoord, A. Revil |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1994-0416
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| Digitales Dokument |
URL |
| Erschienen |
In: The Cryosphere ; 9, no. 2 ; Nr. 9, no. 2 (2015-04-27), S.781-794 |
| Datensatznummer |
250116784
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| Publikation (Nr.) |
 copernicus.org/tc-9-781-2015.pdf |
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| Zusammenfassung |
| A coupled hydrogeophysical forward and inverse modeling approach is developed
to illustrate the ability of frequency-domain airborne electromagnetic (AEM)
data to characterize subsurface physical properties associated with
sublacustrine permafrost thaw during lake-talik formation. Numerical modeling
scenarios are evaluated that consider non-isothermal hydrologic responses to
variable forcing from different lake depths and for different hydrologic
gradients. A novel physical property relationship connects the dynamic
distribution of electrical resistivity to ice saturation and temperature
outputs from the SUTRA groundwater simulator with freeze–thaw physics. The
influence of lithology on electrical resistivity is controlled by a surface
conduction term in the physical property relationship. Resistivity models,
which reflect changes in subsurface conditions, are used as inputs to
simulate AEM data in order to explore the sensitivity of geophysical
observations to permafrost thaw. Simulations of sublacustrine talik formation
over a 1000-year period are modeled after conditions found in the Yukon
Flats, Alaska. Synthetic AEM data are analyzed with a Bayesian Markov chain
Monte Carlo algorithm that quantifies geophysical parameter uncertainty and
resolution. Major lithological and permafrost features are well resolved by
AEM data in the examples considered. The subtle geometry of partial
ice saturation beneath lakes during talik formation cannot be resolved using
AEM data, but the gross characteristics of sub-lake resistivity models
reflect bulk changes in ice content and can identify the presence of a talik.
A final synthetic example compares AEM and ground-based electromagnetic
responses for their ability to resolve shallow permafrost and thaw features
in the upper 1–2 m below ground outside the lake margin. |
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