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The Ovide program. Ovide contributes to the monitoring and the understanding of ocean variability in the northern North Atlantic ocean (transports, water mass properties) An hydrographic section with direct velocity measurements is repeated every 2 years in summer, between Greenland and Portugal.
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The Ovide program Ovide contributes to the monitoring and the understanding of ocean variability in the northern North Atlantic ocean (transports, water mass properties) An hydrographic section with direct velocity measurements is repeated every 2 years in summer, between Greenland and Portugal • FOUREX (A25) section in 1997 • 2002, 2004 • 2006: focus of this talk • 2008 planned and 2010: last occurrence...although 2014-2015?
Circulation in the North Atlantic subpolar gyre, area studied by OVIDE CTO2, LADCP, nutrients, pH, Alk., CFCs (28 depths) Key water masses, relevant for Geotraces
Ovide 2006 transports NAC EGC 11.8 -7.8 -15.3 17.6 MW LSW -7.4 -3.3 1.2 DWBC ISOW DSOW Iceland basin Irminger sea AABW 0.3 West European basin Greenland Portugal
Transient Tracers : CFCs Apparent Ages of different LSW veins in the North Atlantic during OVIDE 2002 (Data from LCM, Roscoff).
Suggestion: coupling a GEOTRACESsection to the reoccupation of OVIDE(2014 or 2015) • Strategy: 2 ships working in parallel (one dedicated to CLIVAR, the other to GEOTRACES) • Strong hydrological framework (many physical oceanographers + modelers) • Key water masses will be documented for tracers (THC, climate related) • IMAGES cores and deep sea corals collected in the same area are currently analyzed: windows for paleo! • Funders will like the « coupling » and this could weight in favor of getting funded.
Transient Tracers : CFCs Vertical section of CCl4. This tracer is used with other CFCs to determine the apparent ages of the different water masses present along the OVIDE section (Data from LCM, Roscoff).
Comparison with 2002 and 2004 EGC NAC EBC Iceland Basin West European Basin Irminger Sea Iberain Plain • Cyclonic circulation in the Irminger Sea weaker in summer 2006 • Westward shift of the subarctic front
Interannual variability in the MOC and DWBC transports between 1997 and 2004. (Data from LPO, Brest)
East Greenland Current Deep Western Boundary Current North Atlantic Current ? Top Layer Bottom Layer Mass and heat transport summary
Conclusions • Main transports and MOC vary jointly in 1997-2002-2004 and 2006 • In May-June 2006, all mass transports collapsed, along with the MOC and the heat transport. • Model results are needed to interpret these synoptic estimates. (Treguier et al. (2006) for variability between Fourex 1997 and Ovide 2002)