Basic Principles of the General Oceanic Circulation 563 



different water types was no chance phenomenon present in June 1938 but is a per- 

 manent feature of the current in these regions (see Fig. 257). 



In the eastern half of the ocean the Atlantic Current divides into two main branches 

 at about 20° W. ; one of these flows north-east past Ireland and with a reduced strength 

 and moderate Constance through the Faeroes — Shetland Channel into the Norwegian 

 Sea and along the Norwegian coast. It is still noticeable in the Arctic Ocean. The weak 

 and variable second branch turns east-south-east towards the French and Spanish 

 coasts (the Portugal Current). The stronger and also more steady Canaries current in 

 the south-eastern North Atlantic cannot be regarded as a continuation of the Gulf 

 Stream (Thorade, 1928). It seems to be advisable to refer to the whole current from 

 the Florida Straits to the Norwegian coast as the Gulf Stream System but to distin- 

 guish six separate parts of this system (Iselin, 1938); the most important are: 



(1) the Gulf Stream close to the coast or the Florida Current (from the Gulf of 

 Mexico to Cape Hatteras) ; 



(2) the Gulf Stream in the open ocean (from Cape Hatteras until north of the 

 Azores) ; 



(3) the Irish Current (from the splitting point until the Faeroes — Shetland sill); 



(4) the Atlantic (or Norwegian) Current (along the Norwegian coast). 



A side branch of the Irish Current flowing from the south of Iceland to its conver- 

 gence with the East Greenland Current is called the Irminger Current. Helland- 

 Hansen and Nansen (1909) deduced the sea surface currents of the Norwegian Sea 

 from an analysis of temperature and salinity in charts and vertical sections (Fig. 157, 

 p. 368). North of the Lofoten the Atlantic current divides into a branch flowing 

 towards north and north-west (towards Spitzbergen) and another one flowing north- 

 east into the Barents Sea (Schulz, 1929). Towards Greenland the East Greenland 

 Current is still wide and strong north of the Denmark Strait. In the central part of the 

 Norwegian Sea there is an extensive area of extended vortices apparently connected 

 with the topography of the sea bottom. 



Southern Hemisphere. The Brazil Current is a continuation of the South Equatorial 

 Current from Cape San Roque southward. Between 15° S. and 20° S. it is still inside the 

 region of the south trade winds. Off" Cape Sao Thome and Cape Frio the main current 

 flowing south-westwards shows a contraction from its eastern (left) side during most 

 months ; from here it follows the continental shelf line fairly close, probably due to the 

 influence of the Coriolis force. Over the shelf a counter current exists which can be 

 regarded as a branch of the current along the Patagonian shelf (Falkland Current). 

 Off the La Plata estuary the eastern part of the Brazil current turns south-eastwards 

 working into each other in a finger-like fashion with the Falkland Current flowing 

 from the south-west. Near the coast the Falkland Current intrudes to the north and 

 north-east as far as 35° S., deflecting the Brazil Current to the east. Between the two 

 opposing currents there is thus a sharp convergence line formed which is clearly shown 

 by the distribution of the oceanographic factors. This gives rise to vortices found in 

 this part of the ocean. The interaction between Falkland and Brazil Current form a 

 southern hemisphere counterpart to the Labrador Gulf Stream system in the Northern 

 Hemisphere, but the first ones are less well developed and of less intensity. 



The area of the West Wind Drift includes the whole of the southern part of the 

 South Atlantic Ocean between about 35° and 63° S. It belongs to the large circumpolar 



