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| Titel |
Particle transport down to the Bari canyon (Southern Adriatic): processes involved in transferring particulate matter to the deep basin |
| VerfasserIn |
Leonardo Langone, Ilaria Conese, Stefano Miserocchi, Alfredo Boldrin, Margherita Turchetto |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250081298
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| Zusammenfassung |
| The Southern Adriatic is known to be an area of dense shelf water cascading and open ocean
convection. The impact of cascading events in transferring fresh organic matter to the deep
benthic community and in producing the wide range of bedforms found on the
continental slope or at its base, has been highlighted in recent years. Particle fluxes and
hydrodynamics were monitored in both branches of the Bari canyon and on the
adjacent open slope from March 2004 to March 2005. Late March of both years were
characterized by colder bottom waters, a notable intensification of bottom currents and
increased particle fluxes, which indicated intense episodes of dense shelf water
cascading.
In March 2009, we deployed a new instrumented mooring at 860 m water depth in a field
of sediment waves situated down current to the Bari canyon. In March 2010, a second
mooring was installed in the northern channel of the canyon, in the same position of mooring
B deployed in 2004. The moorings are still acquiring data and are serviced twice a
year.
Winters 2009, 2010 and 2011 were mild and particularly wet. The Po river discharge
remained relatively high throughout the whole winter. Hence, we expected a not-particularly
dense shelf water formation and a shallow shelf water overflowing off the Adriatic shelf. Very
low near-bottom currents, never exceeding 20 cm s-1, were recorded at both mooring sites.
In addition, the water turbidity showed small amplitude peaks and the water temperature has
showed only minor decreases. Trap fluxes showed much lower values with regards to the
2004-2005 experiment. Nevertheless, they varied both seasonally and interannually. Higher
fluxes were again measured during the spring season with greater values in 2010 and 2011
than in 2009. In the canyon, fluxes were higher than those measured on the sediment wave
field.
In winter 2012, the North Adriatic experienced a severe cold wave with NE Bora winds
and reduced fresh water input from the Po river. The impact of these extreme weather
conditions was the formation of extremely dense shelf water. Mass fluxes increased very
much (up to 11 g m-2 d-1), specially in the offshore station. Mass peaks during 2012 were
up to 5 times higher than peaks of previous years. In the canyon station, currents exceeded 70
cm s-1 and temperature dropped to 12.2Ë C at the near bottom. Surprisingly, the total mass
peak occurred between 16 Feb-1 March, 3-4 weeks ahead of arrival of the North
Adriatic Dense Water, suggesting the delivery of dense shelf water from another
source area, maybe the Middle Adriatic Sea. While is apparent that deep cascading
of dense shelf water is the main process driving the particle transfer thought the
Bari canyon during spring 2012, other processes, such as open ocean convection,
storm-driven shelf-to-canyon particle transport, or shallow dense water cascading, will be
examined as forcing of the particle dynamics during 2009, 2010 and 2011 springs. |
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