Koninklijk Nederlands Instituut voor ZeeonderzoekRoyal Netherlands Institute for Sea Research 1 NIOZ is part of the Netherlands Organisation for Scientific Research (NWO) Merci: C. Millot, I. Taupier-Letage Hans van Haren (on behalf of ANTARES collaboration) Subsidence in the deep Mediterranean

2 Acoustic Doppler current profiler (ADCP) level 3 MILOM, at 169 m above bottom 50 vertical bins of 2.5 m (between 2310 and 2435 m) ANTARES neutrino telescope in W-Med Courtesy: C. Curtil down looking *

3 ANTARES ADCP Overview : sep apr 2007 Current amplitude Vertical current Relatve Echo amplitude: particles “bad” data storeys

4 Baseline and Echo intensity data Current amplitude (Error) Vertical current Baseline+ Echo Amplitude 0.01 m/s ~ 1000 m/day Large downward currents (W)!

5 Some processes in the W-Med causing negative vertical currents - deep-water formation (dw) - meso-scale eddies (ME) - meso-scale currents (NC) ME P A A Alps P Pyrenees *

6 Courtesy: X. Durrieu de Madron and collaborators Gulf of Lions Evidence of DW: negative currents in winter only

7 Other mechanisms following DW: meso-scale eddies? * Chl-a day 69 susp sed day 88

8 Rapid downward motions and eddies: Algerian Basin (no DW) 39° N 37° N 39° N 37° N 38° N 7°E8°E9°E7°E8°E9°E van Haren, H., C. Millot, and I. Taupier-Letage, GRL ANTARES: bioluminescent “particles” mm/s ( dB) m

9 Near-bottom intrusion of dense shelf water forms well defined thermo-haline, turbidity, and fluorescence bottom anomalies Chl-a Fluorescence (µg l -1 ) “New” water stratification; T N ~ 1 hour Courtesy: X. D. de Madron ea T N ~ 5-8 h More effects of DW: deep stratification

10 Some peculiar Antares observations 2008 Current Magnitude m s -1 Vertical Current 10-3 m s-1 Relative Echo Amplitude dB First half year, similar to spring Z (m) Z (m) Z (m)

11 Some peculiar Antares observations 2008 High frequency internal waves Current Magnitude m s -1 Vertical Current m s -1 Relative Echo Amplitude dB First 3 weeks Z (m) Z (m) Z (m)

12 Some peculiar Antares observations 2008 High frequency internal waves (~1 hour)  “strong” stratification Current Magnitude m s -1 Vertical Current m s -1 Relative Echo Amplitude dB Last 5 days Z (m) Z (m) Z (m)

13 Conclusions -Spring 2006 large amounts particles in deep: (bioluminescent) optics confirmed acoustically -Regular strong vertical downward currents (1000 m/day) -Associated with meso-scale motions -No direct evidence for local DW -Deep stratification, following DW?, certainly high-frequency wave motions! The end

14 Some peculiar Antares observations 2008