156 



Salinity of the Ocean, its Variation in Oceanic Space and in Time 



ice (especially around Greenland, Tierra del Fuego and similar places). A special 

 investigation of the annual salinity variation in the open North Atlantic has been 

 made by Smed (1943). 



Neumann (1938) has made a detailed investigation of the annual temperature and 

 salinity variations over twelve five-degree squares for part of the Gulf Stream region 

 between Newfoundland and about 25° W. (north and north-west of the Azores). 

 These variations are presented graphically in detail in Fig. 65. It shows a rapid decrease 



Fig. 65. Annual salinity variations in the North Atlantic between the Newfoundland Banks 

 and the Azores (according to Neumann). 



in the annual amplitude and a displacement of the maximum on moving from the 

 west to the east and south-east away from the Newfoundland Banks, where the large 

 annual change in salinity is due in the first place to seasonal changes in the inflow "of 

 salt with the Labrador Current. This area is the starting point of an annual disturb- 

 ance that spreads out to the east and south-east and gradually diminishes in intensity 

 due to mixing. This phenomenon can be treated theoretically! and comparison with ob- 



t The differential equation governing the process requires that the local change dsjdt of salinity 

 with time and the change by horizontal salinity advection u(8sldx) should be exactly balanced by the 

 change in salinity due to mixing {Aylp)(8Hldy^) so that 



Ss , 8s A^ 8^s 



^r + « — = — ^ — s- 

 8t 8x p 8y^- 



The boundary condition for a linear increase in salinity from y = —m to y = +m on which is 

 superimposed a periodic disturbance at j: = with a maximum amphtude at the zero point and 

 vanishing at >> = ±'n may be formulated as 



S-^o = ^ + ^y + C cos -^ cos — . 

 2m T 



Then a general solution can be given in the form 



s = M + Ny + Cexp \~^'LA^] 

 L 4i>rpiii 



This solution gives a salinity distribution that varies with time in the region from +m to —m as a 

 function of distance and time. The intensity of the disturbance decreases in the direction of flow 

 according to a power of e-function. 



nV 

 COS — COS 



2m 



?-H'-l)l 



