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| Titel |
Long-term oceanographic variability of the South Adriatic Gyre (Mediterranean Sea) and a large-scale climate pattern |
| VerfasserIn |
Laleh Shabrang, Milena Menna, Cinzia Pizzi, Heloise Lavigne, Giuseppe Civitarese, Miroslav Gačić |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250107668
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| Publikation (Nr.) |
 EGU/EGU2015-7379.pdf |
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| Zusammenfassung |
| The interannual variability of the South Adriatic Gyre and its relation to the wind vorticity
and the large climatic pattern (North Atlantic Oscillation - NAO), has been studied using the
time series of satellite altimetry data and ocean surface wind products. The Adriatic Sea is a
source of main component of the dense water for the entire Eastern Mediterranean - Eastern
Mediterranean) Deep water. The cyclonic circulation observed in the South Adriatic area
is mainly sustained by the wind forcing, as suggested by the positive correlation
between the rate of change of the current vorticity and the wind stress vorticity.
Nevertheless, the influence of vorticity advection from the adjacent area (North Ionian
Sea) cannot be ignored and it is more significant during the anticyclonic phase of
Adriatic-Ionian Bimodal Oscillation System. The geostrophic current vorticities
of the South Adriatic and North Ionian Seas are correlated with a time lag of 15
months, which corresponds to an advection speed of ~1 cm/sec. The different wind
configuration, observed during the positive (NAO+) and negative (NAO-) NAO
states, induces the stronger vorticity during NAO- and vice versa. Moreover, the
positive correlation between the NAO index and the frequency of the cold and dry
Northerly wind suggests the strengthening of the winter convection, and of the
consecutive deep water formation, during the NAO+ states. Southern Adriatic area,
being subject to the winter convection, is characterized by the late winter/early
spring algal bloom. Spatially averaged surface chorophyll concentrations were
correlated with the northerly wind frequencies and it was shown that the two biological
productivity regimes likely exist: the subpolar one and the subtropical one depending
on the frequency of windy days. We also show that the bloom timing is a linear
function of the wind frequency and it can vary within the range of almost two months. |
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