The salinity S ^ is found either from the oceanographic tables or from the TS diagram. In 

 the latter case, we proceed along the isoline which corresponds to the given specific volume until 

 we reach the freezing point line, and then we read the corresponding salinity from the X-axis of the 

 TS diagram. This will be salinity 3 -j- • 



Column 8. t is the overall temperature of the mixed layers. It is found from the TS dia- 

 gram, as the temperature corresponding to the specific volume and the mean salinity of the mixed 

 layers at the given level. 



Let us note that although salinity 5^ is greater than the salinity S^, temperature t^ may 

 have different values. If S^ is higher than 5^, temperature tg is always equal to the freezing 

 point. 



Column 9. The difference between columns 5 and 8, or t^-t^- 



Column 10. g j. is the amount of heat in kg-cals released with convective mixing (down to the 

 given level) by each square cm of the sea surface, provided the mean temperature of the mixed 

 layers drops from % to t^, . It is computed by the formula 



^, = 0.1 {tm-t,)p. 



In this computation the specific heat of water is taken as unity. 



Column 11. A5 is the salinity increase, of layers mixed to a given level, necessary for the 

 general specific volume of these layers at the freezing point to equal the specific volume observed 

 at the given level. It is computed as the difference of columns 7 and 6 by the formula 



^s = s,—Sm 



and is entered in the table only when this difference is positive. 



Column 12. i is the thickness (in cm) of the ice formed during convective mixing to the 

 given level. It is computed by the formula 



100 p AS 



where AS is taken from column 11 and Sj,^ from column 6. It is assumed in this formula that 

 the density of ice is 0. 9 and the salinity of the ice is 0. 



Column 13. 9 j is the amount of heat in kg-cal released by each square cm of the sea surface, 

 provided that convective mixing reaches to the given level and ice of thickness i forms. It is com- 

 puted by the formula 



qi = 0.072 /, 



where i is the thickness of the ice in cm taken from column 12. In the formula it is assumed that 

 the density of ice is 0. 9 and that the heat of fusion is 80 gm-cal. 



Column 14. g = g^ + g^ is the sum of the heat released by each cm^ when the sea cools 

 to temperature t^ (coliunn 8) and the heat released when ice of thickness i forms. This is com- 

 puted as the sum of columns 10 and 13. 



75 



