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| Titel |
Large-scale temperature and salinity changes in the upper Canadian Basin of the Arctic Ocean at a time of a drastic Arctic Oscillation inversion |
| VerfasserIn |
P. Bourgain, J. C. Gascard, J. Shi, J. Zhao |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1812-0784
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| Digitales Dokument |
URL |
| Erschienen |
In: Ocean Science ; 9, no. 2 ; Nr. 9, no. 2 (2013-04-10), S.447-460 |
| Datensatznummer |
250018047
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| Publikation (Nr.) |
 copernicus.org/os-9-447-2013.pdf |
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| Zusammenfassung |
| Between 2008 and 2010, the Arctic Oscillation index over Arctic regions
shifted from positive values corresponding to more cyclonic conditions
prevailing during the 4th International Polar Year (IPY) period
(2007–2008) to extremely negative values corresponding to strong anticyclonic
conditions in 2010. In this context, we investigated the recent large-scale
evolution of the upper western Arctic Ocean, based on temperature and salinity
summertime observations collected during icebreaker campaigns and from
ice-tethered profilers (ITPs) drifting across the region in 2008 and 2010.
Particularly, we focused on (1) the freshwater content which was extensively
studied during previous years, (2) the near-surface temperature maximum due
to incoming solar radiation, and (3) the water masses advected from the
Pacific Ocean into the Arctic Ocean. The observations revealed a freshwater
content change in the Canadian Basin during this time period. South of
80° N, the freshwater content increased, while north of
80° N, less freshening occurred in 2010 compared to 2008. This was
more likely due to the strong anticyclonicity characteristic of a low AO
index mode that enhanced both a wind-generated Ekman pumping in the Beaufort
Gyre and a possible diversion of the Siberian River runoff toward the
Eurasian Basin at the same time. The near-surface temperature maximum due to
incoming solar radiation was almost 1 °C colder in the southern
Canada Basin (south of 75° N) in 2010 compared to 2008, which
contrasted with the positive trend observed during previous years. This was
more likely due to higher summer sea ice concentration in 2010 compared to
2008 in that region, and surface albedo feedback reflecting more sun
radiation back in space. The Pacific water (PaW) was also subjected to strong
spatial and temporal variability between 2008 and 2010. In the Canada Basin,
both summer and winter PaW signatures were stronger between 75° N and
80° N. This was more likely due to a strong recirculation within the
Beaufort Gyre. In contrast, south of 75° N, the cooling and warming
of the summer and winter PaW, respectively, suggest that either the PaW was
less present in 2010 than in 2008 in this region, and/or the PaW was older in
2010 than in 2008. In addition, in the vicinity of the Chukchi Sea, both
summer and winter PaW were significantly warmer in 2010 than in 2008, as a
consequence of a general warming trend of the PaW entering in the deep Arctic
Ocean as of 2008. |
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