Geoscience Reference
In-Depth Information
Fig. 6 MDT fields referenced to the full-region average: a the HYCOM MDT (free run) from 1993 to 2010,
b the ATL from 1993 to 2009, c the MICOM from 1993 to 2007, and d the GOCE-based MDT from 1993 to
2009. The color bars are in meters. All the fields are interpolated to a 0.25 resolution grid
expressions of cyclonic circulation in the Greenland Basin, Norwegian Basin and Iceland Sea,
as well as the broadening of the NwAC over the Vøring Plateau and in the Lofoten Basin, i.e.,
signs of a proper western (baroclinic) branch of the northward flowing Atlantic Water. From this
inter-comparison and assessment, it is therefore evident that the GOCE-based geoid provides a
reliable representation of the MDT and mean ocean surface circulation in the Nordic Seas.
Evidently, this is further supported by the mean surface circulation pattern derived from the
climatology of the surface drifter data as shown in Fig.
7
d.
A comparison of the speed of the GOCE-based mean surface geostrophic currents and
corresponding model-based currents for the Nordic Seas is shown in Fig.
8
. In general, it
must be emphasized that the finer spatial model resolution versus GOCE may favor
stronger simulated surface speeds. All models indicate intensified currents at the inflows
from the northeast Atlantic Ocean, and in the boundary (slope) currents of the Nordic Seas.
The ATL model shows a strengthened component of internal circulation in the Nordic
Seas, by very strong currents along all the margins. Regarding the currents over the mid-
ocean ridges and other internal topographic features, it is only the MICOM run that shows
signs of reproducing the level of intensification shown in the GOCE-based speeds, however
only at one location, the Mohn Ridge (as also noticed in Fig.
7
d).
