Let us assume now that a complete intermixing of incomii^ water with the main water mass 

 of a given sea occurs in the entire sea immediately after the influx of the former. In such a case, 

 the mean salinity of the outflowing water, after its intermixing with the inflowing water, will equal 

 the mean salinity of the given sea. 



The intermixing of Inflowing water with the main water mass of a given sea never occurs in- 

 stantly but rather over a long time interval. Because of this, the mean salinity value of a sea is 

 usually a value between the salinity of outflowing and inflowing waters. 



Simple calculations demonstrate that the greater the water volume — in comparison with the 

 volumes of inflowing and outflowing waters — that pass (due to intermixing) through the boundary sur- 

 faces (separating individual water layers from each other) the nearer the mean salinity of the sea to 

 the salinity of the outflowing water. Thus the mean salinity of a sea will be closer to the salinity of 

 the outflowing waters as the pure water balance of the given sea is smaller, the water exchange with 

 adjacent seas in comparison with the general water mass of the given sea is smaller and as the 

 speed of intermixing is greater. 



The balance of moisture and, consequently, the water exchange and salinity for each individ- 

 ual sea can be most readily calculated by measuring the current speeds and salinity at oceanological 

 cross sections across the straits connecting the given sea with the adjacent parts of the ocean. 



The needed formulae are readily derived from the above equations — namely: 



in which Qi and Q2 = areas of crosswise intersection of currents running in opposite directions in 

 straits, u^ and u2 - corresponding mean speeds of the currents. 



The formulae of water balance can be presented differently — namely, in lieu of (1) and (2) we 

 write 



V +Vi + F — V. = consi, (6) 



VS + KA — V^S.2 = const, (7) 



where V = the total volume of a basin, 



S = the mean salinity of the basin. 



It is evident that if one of the components of the balance changes after equilibrium is achieved, 

 a corresponding variation of one or several components of the balance formula will be entailed. 

 This variation will not, of course, occur immediately. 



Assume that, in addition to the water exchange with the adjacent basins, an ice exchange 

 exists. In such a case, the balance formula is as follows: 



V^+F + W^'^V^ + W^', 



(8) 



where 



6 = density of ice. 



62 



