Tides in the Mediterranean and Adjacent Seas 



375 



tides are definitely semi-diurnal, they are of a mixed type in the Belts and 

 become diurnal in the entire Baltic. This is most pronounced in the central 

 Baltic (Libau, Karlskrona) and in the Gulf of Finland. An attempt to re- 

 present the co-tidal lines has been made in Figs. 156 and 157. The semi- 



Fig. 156. Co-tidal lines of the M 2 tide for the Kattegat and Baltic. (Phase in degrees and 



amplitude in cm.) 



diurnal tide shows three amphidromies, namely, one in the south-western 

 Baltic, one in the Gulf of Finland and the third one in the Gulf of Bothnia 

 (all contra solem). The central basin shows a transition from the south-west- 

 ern amphidromy to the others; there is no reason to consider it as a separate 

 amphidromy, as Witting did. The amplitudes show a decrease in the Danish 

 waters and then remain below 1 cm everywhere, except in the south-western 



