410 



Tides in the Mediterranean and Adjacent Seas 



preponderantly semi-diurnal", but it comes already close to the diurnal type. * 

 The tidal current, with rapidly decreasing amplitude and gradual shifting in 

 the phase maintains the same form till about 16°N. ; south of the Dahalach 

 Archipelago there seems to be a "nodal line". 



Defant (1926, p. 185) has made a new computation of the tides of the 

 Red Sea for M 2 and K x which can be expected theoretically on the basis of 

 the more accurate data obtained from the harmonic analysis. The agreement 

 with the observations was again very good. The difference with the first 

 computation was, however, that now the co-oscillating tides dominated, 

 whereas the tide generating forces should only cause slight modifications. 

 Sterneck (1927, p. 129) has been induced by this contradiction with the first 

 attempt to make a mathematical segregation between the co-oscillating tide 

 and the independent tide according to his "Zeriegungs" method. He con- 

 cluded that, for the larger part of the Red Sea, the ratio of the two tides is 

 for M 2 1:3, for S 2 1:4. In the Gulf of Suez this ratio becomes considerably 

 larger. For K x the amplitude of the two tides is approximately equal. 



As we will explain later on (see p. 508) Proudman has expressed the thought 

 that the co-oscillation with the water-masses of the Gulf of Aden and the 

 independent tides, the tides of the Red Sea are influenced by the tides of 

 the solid earth. He has shown how the tides of the solid earth influence those 



Table 55. Comparison between observed and theoretical 

 values of M 2 tide in Red Sea 



* The measurements made by Gedge (1898, see vol. 1/2) according to which there are only 

 diurnal tidal currents in the strait, are based on too short a series of measurements, where, at the 

 time of the equinoxes and quadratures, the semi-diurnal variation becomes of less importance. 



