cross section taken along latitude 5 N, shoved the presence of the inversion 

 in most of the soundings, generally higher in the eastern section. In this 

 cross section and also in the one taken along latitude 10°N, the presence of 

 a second inversion near 600 mh was noticed in most of the soundings . 



In the western equatorial region near the coast of Africa conditions 

 were more variable. Generally, more unstable conditions prevailed there. 

 Most of the soundings in that area showed moisture extending to high levels. 

 A few soundings obtained from the research aircraft earlier in the season 

 showed tendency for an inversion near 85O rab. 



/ In general, the distribution showed a pronounced low inversion over the 

 cool waters in the upwelling areas near the coasts of Somali and Arabia, a 

 general rise in the inversion downstream toward the coast of India and a 

 pronounced tendency for sudden and violent overturning with disturbed weather 

 in the coastal area just west of the Indian coast. The disturbed weather 

 zone along the east coast extended south from about latitude- 20TI; north of 

 this latitude more stable and drier conditions were prevalent, which is of 

 course reflected in the presence of the desert-like conditions of northwest 

 India and west Pakistan. 



SUMMARY AND CONCLUSIONS 



Some remarks should be made concerning the basic assumption behind the 

 method of analysis used. The data were all obtained from a moving platform 

 and in the case of ATLANTIS data covered a period of 7 weeks. The aircraft 

 data mentioned was obtained about a month and a half earlier. They were 

 analyzed to show variations in space, under the assumption that the variations 

 in time were negligible compared to those in space. On the basis of the 

 experience during the 1963 season, we think that this principle holds well. 

 Of course, not all of the details shown by the data can be considered 

 indicative of space variations exclusively. The gross features emphasized 

 above are unquestionably evidence of space variations. The validity of this 

 approach is supported by the fact that the picture derived from the analysis 

 is quite close to the one to be expected considering the factors operating 

 over that area. 



The picture can be summarized as follows: The establishment of the 

 monsoon circulation near the surface over the Arabian Sea in the characteristic 

 manner illustrated in Figure 1 and in reference to the land masses of Africa 

 and Arabia influences greatly the distribution of water temperatures over the 

 Arabian Sea mainly through the processes of upwelling in the western side 

 of the sea. At the same time the oceanic influence on the air mass in the- 

 surface layer combined with a continental air mass that moves eastward in 

 the le-vels upward from about the 900 mb level results in stabilizing the 

 thermal stratification in the western zone of the sea. We have thus a 

 relatively cool moist shallow air mass below and a dry warm mass aloft 

 separated by a thermal inversion and moisture discontinuity. These 



