Response of Permafrost to Changes in Paleoclimate
Solutions to the Stefan problem for the motion of the base of ice-bearing permafrost in response to changes in paleoclimate were obtained using perturbation, finite difference, and finite element methods. Paleotemperature models were used to investigate the thickness response, compare solution metho...
| Main Authors: | , , , |
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| Other Authors: | |
| Format: | Text |
| Language: | English |
| Published: |
1992
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| Subjects: | |
| Online Access: | http://www.dtic.mil/docs/citations/ADP007332 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADP007332 |
| Summary: | Solutions to the Stefan problem for the motion of the base of ice-bearing permafrost in response to changes in paleoclimate were obtained using perturbation, finite difference, and finite element methods. Paleotemperature models were used to investigate the thickness response, compare solution methods, determine the current state of the permafrost, and to determine constraints on the models. The perturbation and finite difference methods used the approximation of linear temperature profiles while the finite element method did not. There was a transient thickness response of about 41 kyr implying that paleotemperature records of greater length are needed for models and that the permafrost loses its memory of past conditions for much longer times. Faster thawing rates, slower freezing rates, and greater variations in thickness were found for the perturbation and finite difference solutions compared to the finite element solution. These appear to be caused by the simplifying assumptions in the former solutions. A lag (20 kyr) exists between changes in surface temperature and thickness response and a small thermal offset is apparent in the finite element solution. Small asymmetries exist in the freezing and thawing rates and thickness response. Paleotemperature models based on ice cores predict current permafrost thicknesses that are too large. |
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