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| Titel |
Variability and changes of Arctic sea ice draft distribution – submarine sonar measurements revisited |
| VerfasserIn |
A. Oikkonen, J. Haapala |
| 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 ; 5, no. 4 ; Nr. 5, no. 4 (2011-10-24), S.917-929 |
| Datensatznummer |
250002750
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| Publikation (Nr.) |
 copernicus.org/tc-5-917-2011.pdf |
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| Zusammenfassung |
| Changes in the mean sea ice thickness and concentration in the Arctic are
well known. However, quantitative information about changes in the ice
thickness distribution and the composition of the pack ice is lacking. In
this paper we determine the ice draft distributions, mean and modal
thicknesses, and their regional and seasonal variability in the Arctic for
the time period 1975–2000. We compare characteristics of the Arctic pack ice
for the years 1975–1987 and 1988–2000. These periods represent different
large-scale atmospheric circulation modes and sea ice circulation patterns,
most evident in clearly weaker Beaufort Gyre and stronger as well as westward
shifted Transpolar Drift during the later period. The comparison of these two
periods reveals that the peak of sea ice draft distributions has narrowed and
shifted toward thinner ice, with reductions in both mean and modal ice draft.
These noticeable changes are attributed to the loss of thick, mostly deformed
ice. Springtime, loss of ice volume with draft greater than 5 m exceeds
35 % in all regions except the Nansen Basin, with as much as 45 % or more
at the North Pole and in the Eastern Arctic. Autumn volume reduction, mostly
of deformed ice, exceeds 40 % in the Canada Basin only, but is above 30 %
also in the Beaufort and Chukchi Seas. During the later period, the volume of
ice category consisting thin, mostly level first-year ice, is clearly larger
than during the former period, especially in the spring. In the Beaufort Sea
region, changes in the composition of ice cover have resulted in a shift of
modal draft from level multiyear ice draft range to values of level
first-year ice. The regional and seasonal variability of sea ice draft has
decreased, since the thinning has been most pronounced in regions with the
thickest pack ice (the Western Arctic), and during the spring (0.6–0.8 m
per decade). |
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