observed and simulated variability of the north atlantic subpolar gyre helge drange & co g. c....

Observed and simulated variability of the North Atlantic subpolar gyre

Helge Drange & CoG. C. Rieber Climate Institute, the Nansen Center, Bergen, Norway Bjerknes Centre for Climate Research, Bergen, Norway

Geophysical Institute, University of Bergen, Norway Nansen-Zhu International

Research Centre, Beijing, China

NOClim-cite

d:

Curry & Mauritz

en (2005); H

atun et al. (

2005)

NOClim-re

levant:

Orvik and Skagseth (2005); M

auritzen et a

l. (2006);

Siegismund et al. (

2006)

Essentially Curry & Mauritz

en, Science, 2005

~300.000 hydrogrphic profiles (NISE)

Orv

ik, K

jell

Aril

d; S

kags

eth,

Øys

tein

(20

05),

Hea

t flu

x va

riatio

ns in

the

east

ern

Nor

weg

ian

Atla

ntic

Cur

rent

tow

ard

the

Arc

tic fr

om m

oore

d in

stru

men

ts, 1

995–

2005

. Geo

ph. R

es. L

ett.,

32,

No.

14,

L14

610

10.1

029/

2005

GL0

2348

7

Orv

ik, K

jell

Aril

d; S

kags

eth,

Øys

tein

(20

05),

Hea

t flu

x va

riatio

ns in

the

east

ern

Nor

weg

ian

Atla

ntic

Cur

rent

tow

ard

the

Arc

tic fr

om m

oore

d in

stru

men

ts, 1

995–

2005

. Geo

ph. R

es. L

ett.,

32,

No.

14,

L14

610

10.1

029/

2005

GL0

2348

7

Orv

ik, K

jell

Aril

d; S

kags

eth,

Øys

tein

(20

05),

Hea

t flu

x va

riatio

ns in

the

east

ern

Nor

weg

ian

Atla

ntic

Cur

rent

tow

ard

the

Arc

tic fr

om m

oore

d in

stru

men

ts, 1

995–

2005

. Geo

ph. R

es. L

ett.,

32,

No.

14,

L14

610

10.1

029/

2005

GL0

2348

7

“...The extreme temperature increase of 1 oC appears, however, to be independent of the current strength. A future challenge here will be to reveal

the cause of this extraordinary warming...”

R

I

F

Altimetry

MICOM

SSH EOF

I

I

F

F

R

R

The subpolar gyre influence

(Häkkinen and Rhines, Science, 2004)

RI

A longer term perspective

Observed and simulated salinity anomalies from about 1970 to present

Observed Simulated

Irminger (I) Faroe (F) Rockall (R)

(inverted)

WNAW

ENAW

Fresh Saline

The gyre shape and the Rockall Trough

Important: Relationship valid for temperature also!

EOF1 Wind stress curl (26%) EOF1 Buoyancy flux (19%)

Red: SSH PC1 Black: SLP PC1 Green: PC1 Wind stress Blue: PC1 Buoyancy flux

Volume of LSW in layers 15 and 16 and the GI

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

The dynamics of the N-Atl subpolar gyre is of key importance for the poleward transport of heat and salt

The dynamics of the N-Atl subpolar gyre is largely governed by winter time bouyancy forcing

Decadal-scale coupled atm-ocean mode possible - needs investigation! (coupled model system required)

Current generation of OGCMs is able to complement observations

NOClim has provided important insight into the variability of the (marine) climate of the N-Atl

Summary: