Density of Water Masses in Ocean, Vertical and Horizontal Density Distribution 197 

 Table 80. Stability in the Atlantic (10^ X E) 



to the observations made by the "Snellius" Expedition (Schubert, 1931) the Philippine 

 Trench shows the values of £■ X 10^ given in Table 81. 



PoLLAK (1954) has given a different definition for the stability which has some ad- 

 vantages in many cases. It gives somewhat different values for E, but differences re- 

 main in the limits. 



Table 81. Vertical stability (10^ x E) in the Philippine Trench according to 

 the observations of the ''Snellius''' Expedition 



It may also be of interest to deal with another equation for the vertical stability 

 which shows clearly the difference of the £-values from the vertical density gradient 

 datjdz which has often been used previously as a measure of stability. The density 

 Ps,i^,j, in situ is calculated from hydrographic tables by applying three correction terms 

 to the value 



The first of these e^, depends only on the pressure p, the second e.,,,, depends on the 

 salinity and the pressure and the third e^.j, depends on temperature and pressure, • 

 Then 



Ps,9,p = 1 + [o'l? + e-j, -f €5, J, -f 6^, J,] 



and 



Ps^ds, &^d&-dT, p — 1 + 



dp 



^d+dd- -f ^j) + ^s+ds,p + ^9+dS, p ^ dr 



