The deep circulation in the Norwegian Sea from subsurface floats

Kjell Arne Mork and Henrik Søiland

Institute of Marine Research
Nordnesgaten 50, P.O. 1870 Nordnes
N-5817 Bergen
Norway

The deep circulation in the two basins of the Norwegian Sea, the
Norwegian and the Lofoten Basin, has for the first time been measured
over several years with the use of subsurface floats, i.e. Argo floats.
Institute of Marine Research has in total deployed nine Argo floats that
are drifting at 1500 m depth. The first three floats were deployed in
year 2002 while the six others were deployed in 2003. The trajectories
of the floats show a cyclonic circulation at 1500 m depth in both two
basins with largest speed in the Lofoten Basin. The currents are
strongest at the rims of the two basins where its speed is about 10 cm/s
in the Lofoten Basin and about 5 cm/s in the Norwegian Basin. The floats
show that the circulation is highly topographic steered and in many
areas opposite directed compared to the surface flow. Even relatively
small topographic features at 3000 m depth influence the circulation at
1500 m depth. The seasonal changes in the drift of the floats and its
relation to the wind forcing have been investigated and the results will
be presented.