In the layers of water below the surface layer_, the influence 

 of the wind is felt only indirectly in the form of lowering the sur- 

 face waters_, which leads to the development of compensating currents 

 at great depths. The principal agent in determining circulation of 

 the subsurface water is the differences in water densities in 

 various parts of the ocean. 



The water which sinks at the subtropical convergence located at 

 about ifO^S latitude forms the Indian Ocean Central Water and as it 

 moves to the north is deflected into an anticyclonic gyre whose cen- 

 ter is located southeast of Madagascar. When this water meets the 

 underwater slopes of Madagascar and Africa it turns to the south and 

 returns to the region where it sank. Here it is renewed by further 

 sinking along the subtropical convergence to a depth of about 600 

 meters in the western part of the ocean. It then bends to the east 

 and completes the anticyclonic gyre. 



The deep circulation of the Indian Ocean is divided into two 

 parts by the Central Indian Ridge at a depth of 3/500 meters. The 

 North Indian Deep Water flows south on both sides of the ridge. On 

 the western side the Atlantic Deep Water which flows around the 

 southern tip of Africa plays a part in the circulation and mixes 

 with the North Indian Deep Water. The spread of Atlantic Deep Water 

 in the Indian Ocean is limited by the Agulhas Basin and the Madagas- 

 car Basin. When this water flows out of these basins it joins the 

 common deep stream toward the east and southeast and loses its 

 identifying properties. South of 30°S latitude the water density in 

 the Indian Ocean is greater than in the Pacific at all depths and as 



^Muromtsev_, Ibid ^ p. 100. 



48 



