The Three-dimensional Temperature Distribution and its Variation in Time 133 



14° 16° 18° 20°C 

 22° 24° 26°C 



500 

 1000 

 1500 

 2000 

 2500 

 3000 

 3500 

 4000 



8° 10° 12° 14° 16° 18° 20° 

 °C 



Fig. 56. Vertical distributions of temperature for four adjacent seas. 



1780-1800 m and at 1600-1620 m) between the Virgin Islands and the northern 

 Lesser Antilles. The Caribbean and Yucatan Basins show similar and almost constant 

 values for the temperature and salinity below sill depth, and it is not easy using these 

 values to determine the sources of the water in each basin. This was even more diffi- 

 cult using the older observations. However, an unequivocal solution was reached 

 only on the basis of the vertical oxygen distribution. Having the same potential 

 temperature (Yucatan Basin 3-79-3-8rC, Caribbean Basin 3-81-3-83°C) the water in 

 the Windward Passage contains more oxygen than that of the Anegada Passage. Since 

 the mean oxygen content at 2500 m (ml/1.) in the Caribbean Basin is about 5-0, in the 

 Yucatan Basin about 5-5-6-0 and in the Gulf of Mexico about 5-0, it follows that the 

 renewal by transport through the Windward Passage and that in the Caribbean Sea 

 is determined by that of the Anegada-Virgin Passage. The depth of the two sills can 

 be deduced very reliably, as shown by Dietrich, from the potential temperatures. 

 Earlier determinations based on the observed temperatures recorded in situ resulted 

 in much too large a depth. The potential temperature along a cross-section through 

 the Anegada-Virgin Passage is shown in Fig. 56a. 



The renewal of the deep water in the Gulf of Mexico is more simple to decide. 

 Since the transport through the Florida Straits with a rather shallow sill depth of 

 about 600 m is not likely to be of great influence, the renewal must come from the 

 Yucatan Basin through the Yucatan Strait (sill depth 1 600 m). 



{e) Vertical Temperature Distribution in Adjacent Seas at Higher Latitudes and in the 

 Polar Regions; Autumn and Winter Convection and Ice Formation 

 The basic condition for the formation of a quasi-homo-thermal state in adjacent 

 seas is the presence of an approximately constant sahnity at all depths below the sill 



