A new Deep Water formed in the NW A new Deep Water formed in the NW Mediterranean in 2005Mediterranean in 2005

J. Font (1), J. Salat (1), M. Emelianov (1), P. Puig (1), A. Palanques (1), A. Julià (1), J.L. López-Jurado

(2), C. González-Pola (3) and J. Flos (4)

(1) Institut de Ciències del Mar CSIC, Barcelona, Spain

(2) Instituto Español de Oceanografia, Palma de Mallorca, Spain

(3) Instituto Español de Oceanografia, Gijón, Spain

(4) Universitat de Barcelona, Barcelona, Spain

(contact: jfont@icm.csic.es)

NW Mediterranean, a well known site for dense water formation (1)

Westen Mediterranean Deep Water (WMDW) Westen Mediterranean Deep Water (WMDW)

Open sea convection

Where:

offshore the Gulf of Lions: MEDOC area (42º N, 5º E)

How:

1. Salty LIW is brought to near surface due to winter convection

2. Mixing with surface “old” AW + intense cooling and evaporation (Mistral wind) = WMDW violent sinking during strong Mistral episodes. LIW upwelling is maintained to compensate sinking.

3. New WMDW spreads in the deep ocean Schott and Leaman, JPO, 1991

NW Mediterranean, a well known site for dense water formation (2)

Western Intermediate Waters (WIW)Western Intermediate Waters (WIW)

Open sea convection

Where:

near the northern continental slope

How:

1. Surface relatively less salty water, “recent” AW brought by the Northern current + intense cooling and evaporation = WIW sinking above the LIW layer (up to 400 m).

2. New WIW spreads along the slope advected to the south by the Northern current.

NW Mediterranean, a well known site for dense water formation (3)

Other dense waters

CascadingCascading

Where:

over the shelf

How:

1. Surface lower salinty (river influenced) water + intense cooling and evaporation (Mistral wind) = dense water sinking to the bottom of the shelf to reach the slope.

2. Cascading over the slope and canyons down to match its density. Typically WIW layer. Exceptionally deeper if winter is very cold, windy or dry

Acronym θ (°C) S σθ (kg·m-3)"recent"AW >13 <37.2 <28.1

"old"AW > 13 38.0-38.2 < 28.9WI W 12.6-13.0 38.1-38.3 28.9-29.0LI W 13.0-13.4 38.48-38.55 29.075

WMDW 12.75-12.82 38-43-38.47 29.115-29.120

NW Mediterranean Water masses

LIW

WIW

WIW

LIW

WMDW

Exceptional 2004-2005 winter

Precipitation on the W Mediterranean catchment area during winter 2004-2005 was very scarce. Minimum absolute values ever recorded in many of the meteorological stations.

From 25 January to 10 March, 2005, air temperatures were lower, especially daily maxima, than the climatological average, and northerlies were strong and persistent

Maximum NCEP heat flux since 1948 (72% above average)

Fevrier 2005:Sur 16 jours de tramontane , le vent a atteint ou dépassépendant quatre jours les 100 km/h.Le 28 Février un record du maximum le plus bas a été battu àPERPIGNAN: 1.5°C (précédent record: 3.8°C en 1934)

Janvier 2005:Sur dix-huit jours de tramontane , le vent a atteint ou dépassépendant trois jours 100 km/h.

From climatological summaries of MétéoFrance for the Mediterranean coast

Sequence of Chl_a daily images

January - March 2005: Dense water formation area (identified by low

Chl_a) very persistent and extense

BARC ELO N A

CATALU NYA

M EN O R C A

M ALLO R C A

M AR SELLA

40º N

42º N

44º N

1º E 3º E 5º E

1000

2000

200

2000

1000

200

200

200

Francoli R.

Foix R.

Llobregat R.Besos R.

Tordera R.

Ter R.

Fluvia R.

Tet R.

Erau R.

P. Rhone R.

G.Rhone R. Durance R.

EbroR.

CIESM Hydro-Changes CSIC mooring 41º 28’ N / 3º 40.4’ E 1845-m depthT, S, and current (October 2003 - July 2005)

EuroStrataform CSIC moorings Cap de Creus C. 200, 500 and 750-m depthT, S, Turb. and current (September 2004 - April 2005)

3º 00' 3º 30'

41º 30'

42º 00'

Ter R.

Fluvià R.

Cap de CreusCanyon

PalamósCanyon

BlanesCanyon

100

200400

600 8001000

12001400

1600

1800

2000

2200

2400

2200

Moorings in NW Mediterranean

Intense events in early 2005, followed by a new warmer, saltier steady state

CIESM Hydro-Changes site Records at 1830 m

Very intense current when the most dense water arrives

3º 4º 5º

42º

43º100

150200

500

1000

2000

2500

EuroStrataform winter 2003-2004

Nov-03 Dec-03 Dec-03 Jan-04 Feb-04 M ar-04 Apr-04

1 11 21 31 41 51 6

1 11 21 31 41 51 6

1 11 21 31 41 5

1 21 31 41 5

1 21 31 41 5

Te

mp

era

ture

(ºC

)

1 21 31 41 5

1 21 31 41 5 Planier

G rand Rhone

Petit Rhone

H erault

Aude

Lacaze-D uhiers

C ap de C reus

Monitoring of 7 submarine canyon heads at 300-m depth

Shelf water cascading, preferably towards the W sector

Palanques, A., Durrieu de Madron, X., Puig, P., Fabrés, J., Guillén, J., Calafat, A., Heussner, S., Canals, M., Boninn, J. (2005). Suspended sediment fluxes and transport processes in the Gulf of Lions submarine canyons. The role of storms and dense water cascading. Marine Geology, submitted.

- 1.5 ºC

3º 00 ' 3º 10 ' 3º 20 ' 3º 30 '42º 30 '

42º 20 '

42º 10 '

150200

500

50

100

200 m

500 m

750 m

Sep-04 O ct-04 Nov-04 Dec-04 Jan-05 Feb-05 M ar-05

0

20

40

60

80

100

0

20

40

60

80

100

Cu

rre

nt

spe

ed

(cm

s -

1)

0

20

40

60

80

100

200 m

500 m

750 m

EuroStrataform winter 2004-2005

Focused study in the Cap de Creus canyon head

Intense (earlier and longer) shelf water cascading

8

10

12

14

16

8

10

12

14

16

Te

mp

era

ture

(ºC

)

8

10

12

14

16

200 m

500 m

750 m

- 3 ºC

+ 70 cm/s

CIESM Hydro-Changes + EuroStrataform sites

Current direction

Diagrama TS per totes les dades de la campanya de l'ACA dels camps llunyà i mitjà l'hivern de 2005

SALINITAT

37.0 37.5 38.0 38.5 39.0

TE

MP

ER

AT

UR

A

9

10

11

12

13

14

15

16

Estacions hivern 05

29.0

27.5 28.028.5

Aigua fonda del Mediterrani Occidental

30,0

29.5

Trabucador

Alcanar

Punta de la Banya

Catalan coast monitoring in winter 2005: shelf stations

WMDW

Open sea: “EFLUBIO-3” cruise B/O “Cornide de Saavedra” 15 March - 6 April 2005

15-22 March

24 March-06 April

Underway surface salinity

Potential density at 25 m

MEDOC area

MEDOC + other open sea areas

Cross-slope section near Barcelona: no front, LIW ascent

Detailed general S diagram: WMDW

O

N

C

••

ThetaS

12,500

12,550

12,600

12,650

12,700

12,750

12,800

12,850

12,900

12,950

13,000

13,050

38,420 38,430 38,440 38,450 38,460 38,470 38,480 38,490 38,500 38,510 38,520

θS of mooring time series

Acronym θ (°C) S σθ (kg·m-3) “recent” AW >13 <37.2 <28.1

“old” AW > 13 38.0-38.2 < 28.9 WIW 12.6-13.0 38.1-38.3 28.9-29.0 LIW 13.0-13.4 38.48-38.55 29.075

WMDW: O 12.75-12.82 38-43-38.47 29.115-29.120 WMDW: N 12.87-12.90 38.47-38.49 29.12 WMDW: C 12.72-12.78 38.45-38.47 29.13

CONCLUSIONS

The anomalously dry, windy and relatively cold 2004 – 2005 winter produced an intense deep convection covering a long period and larger area:

The smaller fresh water inputs and limited supply of recent AW, plus strong winds, produced a widespread cascading over the shelvesrecorded in the coastal monitoring

•Type C WMDW formation

recorded at the mooring while falling downslope to deeper areas of the W Mediterranean and at the Barcelona slope cross-section

A large amount of LIW is brought to near surface over the area typically occupied by the relatively recent AWrecorded by surface underway analysis during the cruise: especially from the MEDOC area to Barcelona and at the Barcelona slope cross-section

• Type N WMDW formation where WIW is typically producedrecorded at many cruise stations: MEDOC area, North and East of Balearic Islands(+ saltier LIW? + more LIW from Sicily channel?)

• Type O WMDW formation in open seasrecorded at many cruise stations: MEDOC area, North and East of Balearic Islands

Summer 2005, open sea

TUNIBAL St. 321 Latitude: 40 40.15 N Longitude: 03 23.30 E 15 July 2005

A new deep water structure is present in the NW Med

Are we sensing the effects of the Eastern Mediterranean Transient?

And for sure the dramatic effects of an anomalously dry and windy winter