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Titel |
Seasonality of intermediate waters hydrography west of the Iberian Peninsula from an 8 yr semiannual time series of an oceanographic section |
VerfasserIn |
E. Prieto, C. González-Pola, A. Lavin, R. F. Sánchez, M. Ruiz-Villarreal |
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 (2013-04-03), S.411-429 |
Datensatznummer |
250018045
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Publikation (Nr.) |
copernicus.org/os-9-411-2013.pdf |
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Zusammenfassung |
Seasonality of hydrographical properties at depth in the western Iberian
margin (eastern North Atlantic) is analysed from a 2003–2010 time series of a
semiannual oceanographic section extending ∼200 nm off Cape
Finisterre (43° N). All water masses down to the
permanent thermocline (2000 dbar) show a consistent seasonal signature in
their thermohaline properties and there is a notable asymmetry between the
slope region and the outer ocean (in the surroundings of the Galicia Bank).
There is overall cooling and freshening of eastern North Atlantic central waters
in summertime, which is larger and deeper-reaching on the slope. In
summertime, Mediterranean Water (MW) gets tightly attached against the slope and
is uplifted, reinforcing its thermohaline signature and diminishing its
presence at the outer ocean. In wintertime the situation reverses, MW seems
to detach from the slope and spreads out to the open ocean, even being observed a
secondary branch around the Galicia Bank. Thermohaline seasonality at depth
shows values up to 0.4 °C and 0.08 in salinity at the lower MW, of
the order of 20% of the overall interannual variability observed during
the whole period. Decomposition of thermohaline changes at isobaric levels to
changes along isoneutral surfaces and changes due to vertical displacements
help analyse the physical processes behind the observed seasonality in
terms of (1) the large-scale seasonality of the subtropical gyre in response
to the seasonal migration of the subtropical high pressure system and
subsequent anomalies in Ekman transport and wind stress curl, (2) the
continental slope dynamics, characterized by summer upwelling, winter
development of the Iberian Poleward Current and Mediterranean water spreading,
and (3) the possible influence of seasonal changes of water mass properties
at their formation sources. |
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