In the austral summers of 2000/2001 and 2002/2003 the Italian CLIMA Project carried out two oceanographic cruises along the northwestern margin of the Ross Sea, where the Antarctic Bottom Water forms. Here there is an interaction between the water masses on the sea floor of the outer shelf and slope with a consequent evolution of benthic nepheloid layers and an increase in total particulate matter. We observed three different situations:(a)the presence of triads (bottom structures characterized by a concomitant jump in turbidity, temperature, and salinity data) and high re- suspension phenomena related to the presence of the Circumpolar Deep Water and its mixing with cold, salty shelf waters associated with gravity currents;(b)the absence of triads with highre-suspension, implying that when the gravity currents are no longer active the benthic nepheloid layer may persist until the suspended particles settle to the seafloor, suggesting that the turbidity data can be used to study recent gravity current events;and(c) the absence of turbidity and sediment e-suspension phenomena supports the theory that as teady situation had been re-established and the current interaction no longer occurred or had finished some time before.

THE NEPHELOID BOTTOM LAYER AND THE DYNAMICS OF THE WATER MASSES AT THE SHELF-BREAK OF THE WESTERN ROSS SEA

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2009

Abstract

In the austral summers of 2000/2001 and 2002/2003 the Italian CLIMA Project carried out two oceanographic cruises along the northwestern margin of the Ross Sea, where the Antarctic Bottom Water forms. Here there is an interaction between the water masses on the sea floor of the outer shelf and slope with a consequent evolution of benthic nepheloid layers and an increase in total particulate matter. We observed three different situations:(a)the presence of triads (bottom structures characterized by a concomitant jump in turbidity, temperature, and salinity data) and high re- suspension phenomena related to the presence of the Circumpolar Deep Water and its mixing with cold, salty shelf waters associated with gravity currents;(b)the absence of triads with highre-suspension, implying that when the gravity currents are no longer active the benthic nepheloid layer may persist until the suspended particles settle to the seafloor, suggesting that the turbidity data can be used to study recent gravity current events;and(c) the absence of turbidity and sediment e-suspension phenomena supports the theory that as teady situation had been re-established and the current interaction no longer occurred or had finished some time before.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11367/20975
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