Thickness of multi-year sea ice on the northern Canadian polar shelf: a second look after 40 years
This paper presents a systematic record of multi-year sea-ice thickness on the northern Canadian polar shelf, measured during the autumn and early winter of 2009–2010. The data were acquired by submerged sonar moored in the Penny Strait where they measured floes drifting south from the notional “las...
| Published in: | The Cryosphere |
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| Main Author: | |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Copernicus Publications
2022
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| Subjects: | |
| Online Access: | https://doi.org/10.5194/tc-16-3181-2022 https://doaj.org/article/526f2911b3144d03b69075c1d101bd50 |
| Summary: | This paper presents a systematic record of multi-year sea-ice thickness on the northern Canadian polar shelf, measured during the autumn and early winter of 2009–2010. The data were acquired by submerged sonar moored in the Penny Strait where they measured floes drifting south from the notional “last ice area” until 10 December, when the ice stopped moving for the remainder of the winter. Old ice comprised about half of the 1669 km long survey. The average thickness of old ice within 25 km segments of the survey track was 3–4 m; maximum keels were 12–16 m deep. Floes with high average draft were of two types, one with interspersed low draft intervals and one without. The presence or absence of thin patches apparently distinguished large floes formed via the aggregation of smaller floes of various ages and deformation states from those of a more homogeneous age and deformation state. The former were larger and of somewhat lower mean thickness (1–5 km; 3.5–4.5 m) than the latter (400–600 m; 6.5–14 m). A calculated accretion of new ice onto the multi-year floes measured in the autumn of 2009 was used to seasonally adjust the observations to thicknesses expected by late winter, when comparative data were acquired in the 1970s. The adjusted mean thickness for all 25 km segments with <math xmlns="http://www.w3.org/1998/Math/MathML" id="M1" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><mo>/</mo><mn mathvariant="normal">10</mn></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="27pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="7bbe21a6d3c3904526b1c58822385702"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tc-16-3181-2022-ie00001.svg" width="27pt" height="14pt" src="tc-16-3181-2022-ie00001.png"/></svg:svg> or more old ice was 3.8 m (sample deviation of 0.5 m), a value indistinguishable within sampling error from values measured in the up-drift ... |
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