188 WATER MASSES AND CURRENTS OF THE OCEANS 



from the coast. Off Port Elizabeth the rise amounts to about 29 cm in 

 a distance of 100 km. To the south of South Africa the greatest volume 

 of the waters of the Agulhas Stream bends sharply to the south and then 

 toward the east, thus returning to the Indian Ocean by joining the flow 

 from South Africa toward Australia across the southern part of that 

 ocean, but a small portion of the Agulhas Stream water appears to 

 continue into the Atlantic Ocean. Owing to the reversal of the direction 

 of the main current to the south of Africa, numerous eddies develop that 

 result in a highly complicated system of surface currents which probably 

 is subjected to considerable variations during the year and to variations 

 from one year to another. 



To the north of lat. 10°S the surface currents of the Indian Ocean, 

 which are probably nearly identical with the currents above the tropical 

 discontinuity surface, vary greatly from winter to summer owing to the 

 different character of the prevailing winds. During February and 

 March, when the northwest monsoon prevails, the North Equatorial 

 Current is well developed, and an Equatorial Countercurrent with its 

 axis in approximately 7°S is present. Along the African east coast, 

 between the Gulf of Aden and lat. 5°S, the current is directed toward the 

 south. In August and September, when the southwest monsoon blows, 

 the North Equatorial Current disappears and is replaced by the Monsoon 

 Current, which flows from west to east. Along the coast of east Africa, 

 where the current is directed north from lat. 10°S, water of the Equatorial 

 Current crosses the Equator, and considerable upwelling takes place off 

 the Somali coast. The Equatorial Countercurrent does not appear to 

 be present in this season. 



Nothing is known as to the motion of the water below the tropical 

 discontinuity in the northern part of the Indian Ocean. The character 

 of the water indicates that no strong currents exist and that only a 

 sluggish flow takes place. 



In the southern part of the Indian Ocean the Antarctic Intermediate 

 Water probably flows north, but the flow must be less well-defined than 

 the corresponding flow in the South Atlantic Ocean, because in the 

 Indian Ocean the Antarctic Intermediate Water loses its typical charac- 

 teristics in a shorter distance from the Antarctic Convergence. The 

 probable flow of the deep water will be discussed later. 



The data from the Indian Ocean are too scanty to permit many 

 quantitative calculations as to the amount of water carried by the dif- 

 ferent branches of the current. The only reliable figure that is available 

 is found in Dietrich's study of the Agulhas Stream, which transports a 

 little more than 20 million mVsec. A transport map similar to the one 

 for the North Atlantic Ocean cannot be constructed. 



The Red Sea. The exchange of water between the Red Sea and the 

 adjacent parts of the ocean takes place through the Suez Canal and 



