| Title | Permafrost modelling in northern Great Slave region, Northwest Territories, Phase 1: Climate data evaluation and 1-d sensitivity analysis |
| Download | Downloads |
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| Licence | Please note the adoption of the Open Government Licence - Canada
supersedes any previous licences. |
| Author | Riseborough, D W; Wolfe, S A ; Duchesne, C |
| Source | Geological Survey of Canada, Open File 7333, 2013, 50 pages, https://doi.org/10.4095/292366  Open Access |
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| Year | 2013 |
| Publisher | Natural Resources Canada |
| Document | open file |
| Lang. | English |
| Media | on-line; digital |
| File format | pdf |
| Province | Northwest Territories |
| NTS | 75L; 75M; 76D; 85I; 85J; 85N; 85O; 85P; 86A; 86B; 86C |
| Area | Yellowknife; Great Slave Lake; Gordon Lake; MacKay Lake; Lac de Gras |
| Lat/Long WENS | -117.0000 -110.0000 65.0000 62.0000 |
| Subjects | surficial geology/geomorphology; engineering geology; Nature and Environment; permafrost; freezing ground; ground ice; ground temperatures; terrain sensitivity; terrain types; terrain analysis; arctic
geology; modelling; mapping techniques; climate, arctic; climate |
| Illustrations | location maps; tables; plots; stratigraphic sections |
| Program | Climate Change Geoscience |
| Released | 2013 03 13 |
| Abstract | Climate variables were examined to evaluate their use in permafrost models, using data for Yellowknife Northwest Territories, Canada as an example. Results suggest that conversion of the annual
temperature cycle to a sine wave is an acceptable approximation, as long as the wave retains the correct values for the annual freezing and thawing degree-day totals. Changes in snow depth can be approximated by a parabolic accumulation function. The
delay of snow cover initiation with respect to the start of the freezing season, the snow accumulation function, and snow density are all critical, whereas end-of-season snowpack evolution is of secondary importance.
Modelling results show that
any difference in substrate materials produces a change in the mean annual temperature at the top-of-perennially frozen/unfrozen ground (TTOP) and annual maximum freezing/thawing layer thickness (AFTT). The greatest differences in TTOP were produced
by changes in the thickness and degree of saturation of the surface organic layer. Intermediate differences were due to differences in substrate materials within and immediately below the annual freezing/thawing layer itself, and the smallest
differences were due to variations in the substrate well below the thickness of the annual freezing/thawing layer. These results suggest that knowledge or consideration of the thickness and moisture content of organic soil veneers will be vital to
permafrost mapping in this environment. |
| Summary | (Plain Language Summary, not published)
Permafrost (ground that remains below 0°C) exists under the combined conditions of a cold climate and suitable terrain properties. In the area north of
Great Slave Lake, permafrost is close to its southern limit, and can be easily disturbed by changes at the ground surface, including climate change. This study provides some initial results as part of a project to map permafrost conditions in the
Northern Great Slave region using computer models. Permafrost conditions were represented using computer simulation of typical terrain conditions in the region, as influenced by the Yellowknife climate. Results show that knowing the thickness and
moisture content of the surface peat layer is important for accurate predictions of permafrost distribution. |
| GEOSCAN ID | 292366 |
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