PREFACE 



It is intended by this study to trace the areal extent of the 

 principal vater masses in the Indian Ocean and the manner in which 

 xhese water aiasses undergo change as they proceed from the area in 

 which they were formed. These changes are accomplished either 

 through mixing of adjacent v/ater masses or as a result of climatic 

 environmental variations. 



The opinions and conclusions of various authors who have made 

 studies of the Indian Ocean are included in the sections describing 

 different parts of the ocean. In addition^ the ocean station data 

 contained in the archives of the National Oceanographic Eata Center 

 have been analyzed to trace the boundaries of water masses. The 

 temperature-salinity diagrams which are presented at the end of the 

 chapters are for selected representative stations and do not include 

 all stations used in the analysis. The stations were selected on 

 the basis of reliability. Most stations were taken from cruises 

 more recent than 1958^ although in some instances early cruises_, 

 such as the E6.na Expedition of 1929^ were employed. The stations 

 used to illustrate the temperature-salinity variations are arranged 

 hy geographic locations into intersecting cross sections^ which show 

 the transition from one water mass to another. In zones of rapid 

 transition the stations are spaced at closer intervals along the 



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