CHAPTER II 

 CHANGES OF TEMPERATURE AND SALINITY 



OF THE OCEAN 



Section 12. The Processes that Change the Temperature 

 and Salinity of the Ocean 



The measurement of temperature and the determination of salinity (or any other physical- 

 chemical property) of sea water can be carried out in two ways: 



The temperature can, for instance, be measured at certain time intervals, at the same points 

 in the sea and at the same depths from mean sea level or, in other words, at the same geograph- 

 ical coordinates; such measurements will give an idea of the variations of heat regime of the sea 

 only in the absence of vertical and horizontal movements of water masses in the given area. With 

 the presence of currents, however, we will obtain the temperatures of various water masses each 

 time by measuring the temperatures at geographical coordinates; the temperature variations can be 

 traced in the moving water mass or, according to a statement by Helland-Hansen, the temperature 

 can be measured in oceano logical coordinates . 



The concept of oceanological and geographical coordinates relative to temperature is deter- 

 mined by the following formula: 



dt_^dt_ d^ 



dT~dT'^ " dx ' 



where dt/dT = the rate of temperature variations affected by local circumstances in the same 

 water mass, i.e., the temperature variation with time in oceanological coordinates, dt/dT= the 

 rate of temperature variations at the same geographical latitude and longitude and at the same depth 

 below the sea surface, i.e. , the temperature variation with time in geographical coordinates, u = 

 current speed, and dt/dx= the horizontal temperature gradient in the sea in the direction of the 

 current. 



It is evident that the second term of the equation characterizes the temperature variation at a 

 given point of the sea, which is caused not only by local conditions but also by the heat influx via the 

 current. In other words, by advected heat. 



The variations of temperature and salinity of the water, in oceanological coordinates, are 

 created almost exclusively at the sea surface. The main processes that raise the temperature of 

 the surface water layers in oceanological coordinates are as follows: 



1 . absorption by the sea of incident and diffuse solar radiation (this is the most important 

 process), 



2. radiation from the warmer atmosphere to the colder ocean, 



3. condensation of atmospheric moisture over the colder ocean, 



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