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equator near the coast of Africa. That mission contributed greatly to our 

 knowledge and understanding of the atmospheric properties and weather 

 features over that oceanic body. Another important source of data were 

 the cruises by the research vessels RV ATLANTIS II and RV ANTON BRUUN . The 

 ATLANTIS II carried out an extensive survey over most of the Arabian Sea 

 during the period August 7 - September 28, 1963. 



The present study is mainly concerned with some aspects of the raob data 

 collected by the ATLANTIS II . A collection of about k^ soundings made aboard 

 the ATLANTIS II were studied and analyzed in various forms which revealed 

 well the general characteristics of the thermal stratification over the ocean. 

 We also had access to 10-12 soundings made aboard the RV ANTON BRUIJN from 

 August 11-26, 1963? and to innumerable dropsondes made by the research 

 aircraft . 



TRACK OF THE ATLANTIS II IN RELATION TO THE FLOW AND 

 WATER TEMPERATURE FIELDS 



The track of the ATLANTIS II in relation to the monsoon circulation is 

 illustrated in Figure 1. The monsoon current shows a significant velocity 

 maximum in the western side of the sea near the coast of Somali, with speeds "^ 

 decreasing downstream. In the mean picture the velocity maximum is around 

 30-35 knots, but velocities of around 50 knots were measured by aircraft in 

 that area. Very significant upwelling of the cold subsurface water is also 

 observed in that area. 



One interesting and significant feature of the flow is that nearly all 

 the surface air that enters into India seems to have an oceanic source 

 originating in the Southern Hemisphere. However, flow charts at some distance 

 above the surface, for example 85O mb, reveal flow off the African Continent 

 and the Arabian peninsula moving eastward toward India. Thus, the southwest 1^ 

 oceanic current is extremely shallow. 



The ATLANTIS II made four latitudinal cross sections between the east 

 and west sides of the ^ea. She cruised from Aden to Bombay along latitude 

 15°N from August 6 to 15' Prom Bombay she cruised westward along latitude 

 20*^ and southward to the region of upwelling near Somali; then eastward along 

 latitude 10°N, arriving in Colombo, Ceylon on September f . From Colombo she 

 proceeded westward along latitude 5°N, to the coast of Africa, then went south- 

 ward arriving in Zanzibar on September 28. 



This track turned out to be quite good from the point of view of a study 

 of the monsoon current. The latitudinal paths were to large extent across 

 the flow in the western Arabian Sea, but nearly parallel to it in the east 

 side. The track from August 23 tp 30 followed for a distance of about 1000 

 miles a direction upstream closely parallel to the flow, terminating in the 

 cold-water region near the coast of Somali . 



