The Three-dimensional Temperature Distribution and its Variation in Time 153 



balance. From the distribution of these factors the ratio of the vertical exchange ^2 to 

 the velocity u of the spreading can be calculated (Defant, 1936). The value of A ^lu 

 is between 2 and 3 over the transverse rises and between 5 and 6 in the troughs, with 

 a maximum value of 10. Because this ratio as a first approximation is proportional 

 to the Prandtl mixing length (see Chap. XII I) and this length is more suited for the charac- 

 terization of a turbulent flow than A 2 the above result therefore means that the mixing 

 length is greater in the troughs than over the rises. In the core of this flow for a 

 narrowing of the gap and corresponding increase in the velocity the mixing is somewhat 

 reduced (more laminar flow), while in basins, on the other hand, the contrary occurs 

 (velocity-decrease, stronger mixing). 



6. Mean Vertically Integrated Temperature for Individual Oceans in Zonal Rings 



Calculations of mean temperatures of parts of the sea, or of particular zones of 

 latitude or for the total ocean, are of course only of statistical value. Krummel (1907) 

 determined the values of some of these mean temperatures on the basis of the hori- 

 zontal charts then available; Table 69. The mean temperature of the total ocean of 

 3-8 °C appears very low especially compared with the surface value of 17-4°C. The 

 decisive factor is the very large water masses of the oceanic stratosphere and the com- 

 paratively shallow oceanic troposphere. The mean values for 10° latitude zones show 

 again the marked decrease of about 5°C between the equator and higher latitudes, but 

 the differences between 40° N, and 30° S. remain, in general, small. This is also true 

 for differences in the values for the three oceans. 



Table 69. Mean vertical integrated temperatures °C for different oceans and the 



total ocean 

 (According to Krummel 1907) 



On the whole, the mean temperature of 3-8 °C for the entire ocean makes a rather 

 cold environment for the living organisms in it, however, they are mainly concen- 

 trated in the upper warmer layers. 



