Tides of the Oceans All 



The fact that the depths of the oceans are not considered, that is, their effect 

 on the shape of the co-tidal lines, produces a certain simplification. The 

 procedure in itself is very simple, but requires an intimate knowledge of 

 the tides. 



According to this method Sterneck (1920, p. 131; 1921, p. 363; 1922, 

 p. 145) has drawn co-tidal lines for all three oceans for the semi-diurnal and 

 the diurnal tide waves.* These maps are the first attempt at cartographical 

 presentation based on a uniform principle. Progressive tide waves have not 

 been considered and, wherever they appear, they are to be regarded as an 

 interference of two standing wave systems. In theoretical support of Sterneck's 

 method, it should be noted that this splitting up into two orthogonal oscillat- 

 ing systems is in itself of a purely formal nature. According to the basic 

 phase selected, it can be solved in an infinite number of ways. Physically 

 the method means that although he considers the tides of the oceans as 

 oscillations of a closed basin, they do not appear as a simple standing wave; 

 but can always be considered as the superposition of two systems of ortho- 

 gonal standing waves (see Defant, 1928, p. 274; 1929, p. 209). This is 

 important because the tides of the different oceans act upon each other and 

 dissipate a great amount of energy on the shelf and on the ice in the polar 

 regions. 



2. Methods used to Incorporate the Observations Presently Available in Maps 

 of the Tides of the Oceans 



The number of coastal localities for which harmonic constants have been 

 computed has increased lately to such an extent that is has become possible 

 to map the oceanic tides, based on many reliable data. 



The International Hydrographic Bureau in Monaco has published, from 

 1930 to 1940 for 2650 localities a list of their harmonic constants, the location 

 of the tide gauges, duration of the observations, highest high water and lowest 

 low water and mean sea level during the period of observation. The British 

 tide tables (1938, Part II) supplement these data by giving for 3500 other 

 localities the constants of the 



M, , S 2 , K L and 1 



tides. However, these constants are not as accurate because they have not 

 been computed from the harmonic analysis but are obtained by applying 

 tidal differences between these stations and the reference stations (see p. 311). 

 The German tide table published in 1940 contain the harmonic constants 

 of the ten principal tides for a large number of coastal stations as they are 



* The first term of this split-up equation for the diurnal tide has a phase h and the co-tidal 

 lines for 6 h and 18 h are nodal lines of this oscillating system. The second term has the phase 6h 

 and high water occurs along the nodal lines at and 12 h. 



