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| Titel |
Changes in the Composition of the Fram Strait Freshwater Outflow |
| VerfasserIn |
Paul Dodd, Mats Granskog, Agneta Fransson, Melissa Chierici, Colin Stedmon |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250133568
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| Publikation (Nr.) |
 EGU/EGU2016-14193.pdf |
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| Zusammenfassung |
| Fram Strait is the largest gateway and only deep connection between the Arctic
Ocean and the subpolar oceans. Monitoring the exchanges through Fram Strait
allows us to detect and understand current changes occurring in the Arctic Ocean
and to predict the effects of those changes on the Arctic and Subarctic climate and
ecosystems.
Polar water, recirculating Atlantic Water and deeper water masses exported from the
Arctic Ocean through western Fram Strait are monitored year-round by an array of moored
instruments along 78∘50’N, continuously maintained by the Norwegian Polar Institute since
the 1990s. Complimentary annual hydrographic sections have been repeated along the same
latitude every September.
This presentation will focus on biogeochemical tracer measurements collected along
repeated sections from 1997-2015, which can be used to identify freshwater from different
sources and reveal the causes of variations in total volume of freshwater exported e. g.: pulses
of freshwater from the Pacific.
Repeated tracer sections across Fram Strait reveal significant changes in the composition
of the outflow in recent years, with recent sections showing positive fractions of sea ice
meltwater at the surface near the core of the EGC, suggesting that more sea ice melts back
into the surface than previously.
The 1997-2015 time series of measurements reveals a strong anti-correlation between
run-off and net sea ice meltwater inventories, suggesting that run-off and brine may be
delivered to Fram Strait together from a common source. While the freshwater outflow at
Fram Strait typically exhibits a similar run-off to net sea ice meltwater ratio to the central
Arctic Ocean and Siberian shelves, we find that the ratio of run-off to sea ice meltwater at
Fram Strait is decreasing with time, suggesting an increased surface input of sea ice
meltwater in recent years.
In 2014 and 2015 measurements of salinity, δ18O and total alkalinity were collected from
sea ice cores as well as the underlying water column in Fram Strait. We use this dataset to
investigate the feasibility of using concurrent δ18O and total alkalinity measurements to
separately identify precipitation, which probably makes up a significant fraction of the
freshwater in Fram Strait, but has so far not been separately monitored. |
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