412 



Tides in the Mediterranean and Adjacent Seas 

 ,sin(136°-y) 



H x = H 



sin88 : 



is the amplitude of the independent tide and 



,sin(y-44°) 



H, = H 



sin 8 8° 



the amplitude of the co-oscillating tide. The two components are graphically 

 shown in Fig. 174; the full-drawn curve gives the co-oscillating tide, the dashed 

 curve indicates the independent tide. The observed values are entered for 



S 2 RTAS K 



M K A P 



20 



10 



O 



-iO 



-20 

 -30 



an 



1000 



2000 



Fig. 174. Distribution of amplitude along the Gulf of Suez and the Red Sea for the co- 

 oscillating tide ( ) and for the independent tide ( ); x, observed values of the 



co-oscillating tide; o; observed values of the independent tide. 



comparison. The agreement between the observations and the theory is still 

 not very good in the Gulf of Suez; it is a great deal better in the Red Sea, 

 with the exception of Massaua and in the vicinity of the nodal lines. Table 55 

 gives in the last column the ratio HJH 2 , both for the theoretical and for the 

 observed values. For the largest part of the Red Sea this ratio is about 3:10, 

 in agreement with the findings of Sterneck.* 



These recent papers have proven that the M 2 tides of the Red Sea are the 

 superposition of an independent tide and a tide co-oscillating with the Gulf 

 of Aden. However, the amplitude and phase can only be fully explained 

 when the tides of the solid earth are taken into consideration: their action is 

 of about the same order of magnitude as that of the tide-generating potential. 

 For their determination very accurate tidal observations are required, more 

 accurate than those which are presently available. The frictional influences 



* The deviations in Defant must be mainly attributed to the fact that, when determining the 

 independent tide, he did not take into account a canal section in the south about 190 miles long, 

 north of Perim, which omission is not justified. 



