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| Titel |
Time and space variability of freshwater content, heat content and seasonal ice melt in the Arctic Ocean from 1991 to 2011 |
| VerfasserIn |
M. Korhonen, B. Rudels, M. Marnela, A. Wisotzki, 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. 6 ; Nr. 9, no. 6 (2013-12-02), S.1015-1055 |
| Datensatznummer |
250085280
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| Publikation (Nr.) |
 copernicus.org/os-9-1015-2013.pdf |
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| Zusammenfassung |
| Changes in the hydrography of the Arctic Ocean have recently been reported.
The upper ocean has been freshening and pulses of warm Atlantic Water have
been observed to spread into the Arctic Ocean. Although these changes have
been intensively studied, salinity and temperature variations have less
frequently been considered together. Here hydrographic observations, obtained
by icebreaker expeditions conducted between 1991 and 2011, are analyzed and
discussed. Five different water masses in the upper 1000 m of the
water column are examined in five sub-basins of the Arctic Ocean. This allows
for studying the variations of the distributions of the freshwater and heat
contents in the Arctic Ocean not only in time but also laterally and
vertically. In addition, the seasonal ice melt contribution is separated from
the permanent, winter, freshwater content of the Polar Mixed Layer. Because
the positions of the icebreaker stations vary between the years, the
icebreaker observations are at each specific point in space and time compared
with the Polar Science Center Hydrographic Climatology to separate the
effects of space and time variability on the observations. The hydrographic
melt water estimate is discussed and compared with the potential ice melt
induced by atmospheric heat input estimated from the ERA–Interim and
NCEP/NCAR reanalyses. After a period of increased salinity in the upper ocean
during the 1990s, both the Polar Mixed Layer and the upper halocline have
been freshening. The increase in freshwater content in the Polar Mixed Layer
is primarily driven by a decrease in salinity, not by changes in Polar Mixed
Layer depth, whereas the freshwater is accumulating in the upper halocline
mainly through the increasing thickness of the halocline. This is especially
evident in the Northern Canada Basin, where the most substantial freshening
is observed. The warming, and to some extent also the increase in salinity,
of the Atlantic Water during the early 1990s extended from the Nansen Basin
into the Amundsen and Makarov basins, while the warm and saline inflows
occurring during the 2000s appear to be confined to the Nansen Basin,
suggesting that the warm and saline inflow through Fram Strait largely
recirculates in the Nansen Basin. |
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