Evolution of the firn pack of Kaskawulsh Glacier, Yukon: meltwater effects, densification, and the development of a perennial firn aquifer
<p>In spring 2018, two firn cores (21 and 36 m in length) were extracted from the accumulation zone of Kaskawulsh Glacier, St. Elias Mountains, Yukon. The cores were analyzed for ice layer stratigraphy and density and compared against historical measurements made in 1964 and 2006. Deep meltwat...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2021-04-01
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| Series: | The Cryosphere |
| Online Access: | https://tc.copernicus.org/articles/15/2021/2021/tc-15-2021-2021.pdf |
| Summary: | <p>In spring 2018, two firn cores (21 and 36 m in length)
were extracted from the accumulation zone of Kaskawulsh Glacier, St. Elias
Mountains, Yukon. The cores were analyzed for ice layer stratigraphy and
density and compared against historical measurements made in 1964 and 2006.
Deep meltwater percolation and refreezing events were evident in the cores,
with a total ice content of <span class="inline-formula">2.33±0.26</span> m in the 36 m core and liquid
water discovered below a depth of 34.5 m. Together with the observed ice
content, surface energy balance and firn modelling indicate that Kaskawulsh
Glacier firn retained about 86 % of its meltwater in the years 2005–2017.
For an average surface ablation of 0.38 m w.e. yr<span class="inline-formula"><sup>−1</sup></span> over this period,
an estimated 0.28 m w.e. yr<span class="inline-formula"><sup>−1</sup></span> refroze in the firn, 0.05 m w.e. yr<span class="inline-formula"><sup>−1</sup></span> was retained as liquid water, and 0.05 m w.e. yr<span class="inline-formula"><sup>−1</sup></span> drained or
ran off. The refrozen meltwater is associated with a surface lowering of
<span class="inline-formula">0.73±0.23</span> m between 2005 and 2017 (i.e., surface drawdown that has
no associated mass loss). The firn has become denser and more ice-rich since
the 1960s and contains a perennial firn aquifer (PFA), which may have
developed over the past decade. This illustrates how firn may be evolving in
response to climate change in the St. Elias Mountains, provides firn density
information required for geodetic mass balance calculations, and is the
first documented PFA in the Yukon–Alaska region.</p> |
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| ISSN: | 1994-0416 1994-0424 |