Internal Waves 



545 



explain the phase distribution of Table 93. The average phase for the whole 

 layer from surface to 800 m is 10 9 h. 



In the case of the diurnal wave the distribution is more irregular in the 

 phase as well as in the amplitude. Here, too, however, the smallest amplitude 

 will be found at the depth of 100 m. The elliptic shape of the current diagrams 

 proves the influences of the Coriolis force in the formation of all internal 

 waves in the open ocean. But the current diagrams are very flat, especially in 

 the case of the semi-diurnal tide. With few exceptions they rotate cum sole, 

 as the theory requires. 



Lek (1938, p. 69), in his discussion of the observations of the "Snellius" 

 Expedition, investigates station 253>a particularly thoroughly. The obser- 

 vations for this station (1°47-5'S., 126°59-4'E., 23 and 24 June 1930) are very 

 complete. Table 94 presents the data which were deducted from the ob- 

 servations. A discussion of the table is hardly necessary. Figure 226 shows 



40 



30 



20 



20 



■30 



C 8 



12 16 20 



8 



Fig. 226. Diurnal + semi-diurnal vertical displacements in various depths at "Snellius" 



Anchor Station 253a (Lek). 



a graphical presentation of the vertical displacements at the various depths, 

 as a result of the superposition of the semi-diurnal and diurnal components. 

 The resulting complicated picture of the displacements and their importance 

 will be easily recognized. The maximum of 63 m occurred at a depth of 

 250 m. Lek and Fjelstad applied Fjelstad's theory to this case. The velocities 

 of progress for the first four waves follow; below the velocities are the wave 

 lengths if the period is 24 h : 



K 



234, c 2 = 116, c 3 = 77, c i = 58 (cm/sec) 

 210, A 2 = 104, A 3 = 69, A 4 = 52 (km) 



35 



