Geoscience Reference
In-Depth Information
- the branch rises toward the Equator in the Pacific, comes to
supply the thermocline circulation, continues to warm and rises to the
surface, describing several loops in the equatorial Pacific before
reaching a depth level in the west, where it can cross the Indonesian
Straits to enter the Indian Ocean;
- it crosses the Indian Ocean to reach the coasts of Madagascar and
comes to supply the Agulhas Current to the south-east of Africa. The
Agulhas Current is joined, in the Indian Ocean by a branch coming
from the Antarctic Circumpolar Current;
-this water mass flows around Africa and enters the
Atlantic Ocean in intermediate and surface layers by the
Benguela Current and also in the form of large eddies; another
branch also comes from the Antarctic Circumpolar Current in the
South Atlantic;
- it reaches the Equator and after several loops of recirculation in
its equatorial circulation, it crosses the Equator;
- it returns to the North Atlantic Ocean through the large western
boundary currents, the North Brazilian Current, the Florida Current
and then the Gulf Stream;
- it circulates several times in the anticyclonic Atlantic circulation
before joining the North Atlantic Drift, then the Norwegian Current,
which permits it to return to its region of origin.
This very schematic representation is useful for putting the
communication between oceanic basins and the critical role of certain
regions (the Indonesian Straits, the Cape of Good Hope, etc.) into
relief, for showing the role of convection regions (the North Atlantic)
and subduction (to the north of the Antarctic Circumpolar Current)
and the ascents into the thermocline and into equatorial circulation, for
contrasting residence times in equatorial regions (loops of some years
duration), in temperate regions (loops of some decades duration) and
in the rotation around the Antarctic, for showing the importance of
western boundary currents and the transfer times associated with
them.
