1NIOZ is part of the Netherlands Organisation for Scientific Research (NWO)

Koninklijk Nederlands Instituut voor ZeeonderzoekRoyal Netherlands Institute for Sea Research

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 bottom50 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 2005 - apr 2007

Current amplitude

Verticalcurrent

Relatve Echo amplitude:particles

“bad” data

storeys

4

Baseline and Echo intensity data

Current amplitude

(Error)Verticalcurrent

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

PA

A Alps P Pyrenees

*

6

Courtesy: X. Durrieu de Madron and collaborators

Gulf of Lions

Evidence of DW: negative currents in winter only

7

Rapid downward motions and eddies: Algerian Basin (no

DW)

39°N

37°N

39°N

37°N

38°N

38°N

7°E 8°E 9°E 7°E 8°E 9°E

van Haren, H., C. Millot, and I. Taupier-Letage, GRL 2006.

ANTARES: bioluminescent “particles”

+10--20 mm/s(5- -10 dB)

1900-2400 m

600300

8

Other mechanisms following DW: meso-scale

eddies?

*

Chl-a day 69

susp sed day 88

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; TN ~ 1 hour

Courtesy: X. D. de Madron ea

TN ~ 5-8 h

More effects of DW: deep stratification

10

Some peculiar Antares observations 2008

CurrentMagnitude10-3 m s-1

VerticalCurrent

10-3 m s-1

Relative Echo Amplitude

dB

First half year, similar to spring 2006

2.5 m bins

11

Some peculiar Antares observations 2008

Low and High frequency internal waves

CurrentMagnitude10-3 m s-1

VerticalCurrent10-3 m s-1

Relative Echo Amplitude

dB

First 3 weeks 2009

12

Some peculiar Antares observations 2008

High frequency internal waves (~1 hour) “strong” stratification

CurrentMagnitude10-3 m s-1

VerticalCurrent10-3 m s-1

Relative Echo Amplitude

dB

Last 5 days 2008

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

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Some peculiar Antares observations 2008