Tides of the Oceans 481 



of the open ocean. A sufficient number of cases illustrating this fact, can be 

 found in the maps. An accurate analysis of the entire phenomenon is still 

 lacking. The research on the tides of shelf regions along selected lines will 

 be facilitated after high-sea gauges will have been constructed and tried. 

 The distribution of characteristic number of tide F = (A^ 1 + (9 1 )/(M 2 +S , 2) 

 along the ocean coast is given in Chart III. Contrary to other oceans, the 

 coasts and islands of the Atlantic Ocean show a marked predominance in the 

 semi-diurnal tidal form, nearly everywhere the ratio determining the type of 

 the tide remains below the theoretical value of 



M^S 2 = ° 68 ' 



along the European and African coasts it seldom exceeds 010. This special 

 position the Atlantic Ocean is not the result of high amplitudes of the semi- 

 diurnal tides, but rather of the smallness of the diurnal tides, for the spring 

 tide range of the diurnal tide remains below 40 cm generally disregarding 

 local exceptions. 



In other oceans the diurnal tides are much stronger; in the Pacific Ocean 

 the mixed type is predominant; in the Indian Ocean we find in equal quan- 

 tities both semi-diurnal and mixed, predominantly semi-diurnal type. The 

 purely diurnal type of tides are restricted to locally, very limited areas, con- 

 sidering the wide expanses of the ocean. They can of course be found in the 

 centre of the semi-diurnal amphidromies and along the nodal lines, where 

 the amplitudes of the semi-diurnal tides decrease very much. The remarkable 

 occurrence of high characteristic tide numbers (Formzahl) is thus explained 

 very easily. 



We will now discuss as briefly as possible in some detail, the main phe- 

 nomena of the tides of the three oceans. In Tables 80, 81 and 82 can be 

 found a compilation of the harmonic constants of selected coastal localities 

 and islands. They were selected according to their importance for the 

 character of the tides. 



4. The Mo Tide as the Typical Tide Wave of the Semi-Diurnal Tides 



(a) Atlantic Ocean (Table 80 J 



In the Southern Atlantic Ocean the tide wave travels from south to north 

 over the entire width of this ocean. Large disturbances appear on the Pata- 

 gonian Shelf. From a line running from the Falkland Islands to the north- 

 eastern tip of Tierra del Fuego then north of the Gulfo San Jorge the phase 

 increases by a full 360° and then there is a further increase by the same amount 

 up to east of Bahai Banca. This is due to two amphidromies caused by the 

 co-oscillation of the wide shelf extending out of the southern part of the South 

 American with the open ocean. North of these areas there is over a relatively 

 short distance an increase in the phase of more than 150° which, coinciding 



31 



