Tides in the Mediterranean and Adjacent Seas 



435 



This value is sufficiently close to the period of the semi-diurnal tides for 

 explaining the strong increase of the ranges at the closed end of the gulf. 

 However, the very shallow depth of this area is also partly responsible for 

 this increase. 



17. The Tides of the Gulf of Mexico 



In the entire American Mediterranean Sea the tides are weakly developed. 

 This is not only true for the Caribbian itself, but also for the entire Gulf of 

 Mexico, in which the tidal ranges nowhere exceed 0-7 m (2-3 ft). A particularly 

 characteristic feature is the conspicuous weakening of the semi-diurnal tides, 

 so that in this adjacent sea the establishment becomes practically unusable. 

 The tide is governed by the extreme lunar declinations instead of by the 

 semi-monthly variation of the spring and neap tides. In most localities the 

 tides are diurnal and the amplitudes and phases of the semi-diurnal wave 

 show up only in the results of the harmonic analysis. However, their am- 

 plitudes are small compared to those of K x and O x , so that the ratio de- 

 termining the character mostly exceeds 1 and will even attain, at the northern 

 side of the gulf, a maximum of > 9. In the Caribbean the diurnal tides are 

 still predominant and the contrast in amplitudes between the Atlantic side 

 and the Caribbean side of the islands which separate these seas is sharp 

 (e.g. on Puerto Rico, Ponce has 8-40, San Juan 0-91). 



Table 64. Harmonic constants for the Gulf of Mexico 



For thirteen localities of the Gulf of Mexico, more or less evenly distributed 

 around the Gulf, the harmonic constants are known (Table 64) but, unfor- 

 tunately, only for few localities of the Caribbean. Therefore a detailed in- 

 vestigation of the tides in the Caribbean cannot be performed. 



28* 



