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Trans-Atlantic Linkages- via the subpolar gyre
Hjálmar Hátún
SeaWiFS-based chlorophyll in selekt
Chl [mg m-3
]
0.01
0.1
1
10
ASOF - Halifax - 08
Co-authors: M. R. Payne, G, Beaugrand, P. C. Reid, A. Sandø, H. Drange, B. Hansen, J. A. Jacobsen, D. Bloch
Rockall
IrmingerCurrent
Faroe Current
(Hatun et al., Science 2005)
The Subpolare Gyre and the marine climate
RI
Irminger Current (obs.)
Rockall (obs.)
Gyre index
Record high T and S
The Subpolare Gyre and the marine climate
2.The Subpolar Gyre andPlankton
Continuous Plankton Recorder (CPR) (SAHFOS, Plymouth)
Towing lines since the 1940s
Area south of Iceland
SSH (temperature og currents)Hátún et al., Science, 2005
Phytoplankton
Sea Surface TemperatureBeaugrand, Science 2002
Calanus finmarchicus
”Gyre pattern”
2. SPG and planktonPhytoplankton
Time-development of the ”gyre-mode”
SSH
PCI
SST
Calanus finmarchicus
SST
2. SPG and plankton
Less
Cal
. F
in.
Amount of zooplankton with relatively warm water affinities
(boreal)
CTA: Cold-Temperate Assemblagecalanoid copepods Aetidus armatus, Pleuromamma robusta, Acartia spp. and Metridia lucens.
2. SPG and planktonZooplankton
3.The Subpolar Gyre andPelagic Fish (blue whiting)
Stor endringer i kolmule bestanden
Largest fishery in the North Atlantic!
3. SPG and blue whiting
Large mid-1990s increase
Warm (1998-2003)Cold (1990-1996)
Spatial Shift(Catches – all nations)
1997
3. SPG and blue whiting
Western region
East-West index = (Faroese landings from western region)/
(total faroese landigs)
Blue whiting migration
Western index Gyre index
Pilot whale migration
Pilot whale migration
(Catch in NE area)/(total catch)
Long-term pilot whale migration
Prediction
Reversal in 2005-2006!
Is this causing the poorrecruitments during 05-06?
Good recruitment conditionsshould resume
Atmospheric forcing
• Katja Lohmann, Helge Drange and Mats Bentsen: What caused the strong weakening of the North Atlantic subpolar gyre post 1995?, Submitted. for GRL
0-wind stress curl
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