vater rich in phosphate could only be explained through the process 

 of upwelling. Circulation between the Pacific Ocean and Indian 

 Ocean has also been related to the upwelling which occurs in the 

 region of the Arafura Sea. Water which rises toward the surface is 

 replaced at intermediate depths by water from the Banda Sea. In 

 this way the subsurface water of the northeast Indian Ocean between 

 Indonesia and Australia is renewed by water which comes indirectly 

 from the Pacific Ocean by way of the Banda and Arafura Seas. 

 Surface Water Properties . The Bay of Bengal is distinguished by 

 the contrast in properties of the water masses vhich occupy the sur- 

 face layer to a depth of 100 to I50 meters. La Fond has divided the 

 surface waters of the western part of the bay into three distinct 

 water masses. At any particular season these water masses are found 

 at approximately the same locations although they do migrate season- 

 ally in response to the monsoon circulation. The three vater masses 

 referred to are the Northern Dilute Water, a transition water, and 

 the Southern Bay of Bengal Water. 



The Northern Dilute Water is formed at the head of the bay near 

 the mouths of the large rivers vhich empty into this area. The 

 Ganges and Brahmaputra Rivers discharge the greatest volume of fresh 

 vater with the major dilution taking place in the fall. The Irawaddy, 

 Mahanadi and other rivers add to this volume and bring the estimated 

 discharge of fresh water to 10 cubic meters during the fall season. 

 This river water is then mixed by tidal action and currents with the 



^E. C. La Fond, "On the Circiaation of the Surface Layers off 

 the East Coast of India," Andhra University Memoirs in 'Oceanography , 

 II (Waltair: Andhra University, I958), pp. 1-11. 



28 



