Water masses and thermohaline

variability in the Atlantic Ocean:

consequences for CANT accumulation.

Instituto Nacional de Meteorología , Madrid 14-15, Febrero, 2005

Seminario Acción Especial CLIVAR-España

Fiz F. Pérez, Aida F. Ríos, Marta Álvarez, Fiz F. Pérez, Aida F. Ríos, Marta Álvarez, Instituto de Investigaciones MarinasInstituto de Investigaciones Marinas

CSIC, VigoCSIC, Vigo

Decadal changes of -S relationship of the Eastern North Atlantic Central Water (ENAW) by Pérez, F.F., A.F. Ríos, B.A. King, R.T. Pollard. Deep-Sea Research, 1995.

Carbon dioxide along WOCE line A14: Water masses characterization and anthropogenic entry by Ríos, A. F.et al. Journal Geophysical Research, Vol. 108 2003.

Physical and biogeochemical transport structure in the North Atlantic subpolar gyre by Álvarez M., F.F. Pérez, H. Bryden, A.F. Ríos. Journal of Geophysical Research 109 2004

The unaccounted role of Mediterranean water in the draw-down of anthropogenic carbon by Álvarez M. Fiz F. Pérez, D. R. Shoosmith and H. L. Bryden. Journal of Geophysical Research in revision

Salinity35.4 35.6 35.8

Po

ten

tial

Tem

pera

ture

10

11

12

13

14

15

(41.7,10)/95

(42.1,10.3)/90

93/MORENA I

90/Disc-189

95/MPH 495

91/Darwin-58

Pérez et al. ,2000.Pérez et al. ,2000.

YEAR1965 1970 1975 1980 1985 1990 1995 2000

Salin

ity a

t 27.

1

35.6

35.7

35.8

Nor

ther

ly W

ind

Stre

ss (1

0-3

N.m

-2)

-40

-20

0

20

40

60

A

ccum

ulat

ive

anom

alie

s of

Riv

er D

isch

arge

s (k

m3/y

ear) -40

-30

-20

-10

0

10

20

30

40

Acc

umul

ativ

e an

omal

y of

NA

O

-35

-30

-25

-20

-15

-10

-5

0

5

NAO

ENACW saline change, NAO and RunoffENACW saline change, NAO and Runoff

Pérez et al. ,2000Pérez et al. ,2000..

WO

CE A

-14

WO

CE A

-14

WO

CE

A-1

4W

OC

E A

-14

3EQ51015202530354045

1500

1000

500

0

De

pth

(m

)

ºNºS

C ANT

SAF STF STG SEC SEG ECSSAZ

ºNºS

3EQ51015202530354045

5000

4000

3000

2000

1000

0

De

pth

(m

)

Ríos et al., 2003Ríos et al., 2003

AAIWAAIW

AAIWAAIW

AAIWAAIW

SAIWSAIW

Ríos et al., 2003Ríos et al., 2003

Anthropogenic COAnthropogenic CO22 and CFC-age along the AAIW maximum and CFC-age along the AAIW maximum

MW MW

at 1000 mat 1000 m

-0.1 -0.05 0 0.05 0.1 0.15 0.2 0.25-5500

-5000

-4500

-4000

-3500

-3000

-2500

-2000

-1500

-1000

-500

0

Sv per 20 m

Baroclinic MASS Transport

0.4 Sv

3.0 Sv

-3.4 Sv

Alvarez et al. JGRAlvarez et al. JGR

155 kmol.s-1 of Anthropogenic CO2

The MW is formed from 2.3 Sv of The MW is formed from 2.3 Sv of ENACW and 0.3 Sv of AAIW. ENACW and 0.3 Sv of AAIW. Part of this transformation (0.7 Sv) Part of this transformation (0.7 Sv) occurs inside the Mediterranean Seaoccurs inside the Mediterranean Sea

The MW formation drives a Cant draw-The MW formation drives a Cant draw-down and a salinity increase of MW down and a salinity increase of MW because the ENACW entrained when MW because the ENACW entrained when MW is formed is saturated of Cant and its is formed is saturated of Cant and its salinity is also increasing in 0.1 per salinity is also increasing in 0.1 per decade.decade. This mechanism could be a negative This mechanism could be a negative feedback in future climate scenarios.feedback in future climate scenarios.

2.7 Sv MW0.7 Sv ENACW

0.3 Sv LSW-0.3 Sv AA

Subpolar North Atlantic

Relevance of the Subpolar North Atlantic:- area of deep water formation,

- large capacity to store and transport heat and CO2.

WOCE A25 or 4x section - August-September 1997

- UK WOCE section from Vigo to Cape Farewell,

Water Masses along 4x: Mass (Sv) and CANT Trps (kmol/s)

10.310.3 SvSv2.92.9 SvSv

1.71.7 SvSv

5.6 Sv5.6 Sv-5.4 Sv-5.4 Sv

0.9 Sv0.9 Sv

--8.88.8 SvSv

--6.06.0 SvSv-1.5 Sv-1.5 Sv

484 484 kmol/skmol/s

-36-36 kmol/skmol/s

-274-274 kmol/skmol/s

0 0 kmol/skmol/s

-324-324 kmol/skmol/s159159 kmol/skmol/s

174174 kmol/skmol/s

4848 kmol/skmol/s

-113-113 kmol/skmol/s

ENACWENACW SAIWSAIW

AAIWAAIW

MWMW

LDWLDW

EGCEGC LSWLSW

ISOWISOWDSOWDSOW

Alvarez et al. 2004Alvarez et al. 2004

The role of Subpolar North Atlantic

In the subpolar North Atlantic about 21 Sv of warm waters is transformed in deep and cold waters releasing 0.7 Pw of heat to the atmosphere.

0.33 Gt of anthropogenic CO2 are transported to the north, a 14% is accumulated in the subpolar North Atlantic and 0.28 Gt of anthropogenic CO2 goes south with deep waters.