Tides in the Mediterranean and Adjacent Seas 



429 



end (y = 1) respectively. As a is roughly 60 and b = 6 cm, it appears that 

 there is a nodal line near y = 095, which is very close to the northern outlet 

 of the Strait of Tsushima into the Sea of Japan. The rotation of the earth 

 transforms it into an amphidromy which will be well developed, inasmuch 

 as the tidal currents are rather strong (see Table 61 and Nisida(1927, 1928, 

 1930)). This has also been observed. In the entire Sea of Japan, up to 



Table 61. Currents in the western and eastern canal 

 of the Tsushima Strait 



Depth 



Average current 



Semi-diurnal current 



Diurnal current 



Velocity 

 (cm/sec) 



Direction Velocity Direction 

 (°) (cm/sec) I (") 



Phase 

 (h) 



Velocity | Direction j Phase 

 (cm/sec) (°) (h) 



Western canal: 25-26 April 1928; (age of moon, 5-6 days; declination 25-7-24-4° N.). 



5 m 



100 m 



4-3 

 10-3 



3-1 

 91 



Eastern canal: 19-20 October 1929; (age of moon, 16-17 days; declination ll-8-17-4°N.). 



5m 



100m 



5-6 

 11-6 



50 

 110 



about 45° N. lat., high water occurs at the same time (around 3 h), and the 

 range is very small (spring height along the coasts of Honshu and Hokkaido 

 about 16 cm, at the coast of Korea about 20 cm). In the northern outlet 

 of the Sea of Japan, in the Gulf of Tartary, there is another well-developed 

 amphidromy whose centre is located in the southern section, not far from 

 the passage to the open sea. Here also its existence is confirmed by theoretical 

 considerations by Ogura (1923, p. 89). With a length of the Gulf of about 

 750 km (465 miles) and a mean depth of 250 m (820 ft), the natural period 

 is 8-3 h and v = 0-68, so that there is a nodal line very close to the opening. 

 The increase in amplitude towards the north is a result of the orographical 

 configuration of the Gulf, but also of the fact that v is close to the resonance 

 value. 



The diurnal tide also shows an amphidromy in the Strait of Tsushima, 

 with its centre displaced unsymmetrically towards the coast of Korea. The 

 range 2(^ + 01) is in the south about 80 cm, and decreases towards the north, 

 on the Japanese side as far as 40 cm, on the Korean side to about 12 cm. 

 It maintains this order of magnitude all over the Sea of Japan, and high 

 water occurs for K x in the east almost simultaneously at 23 h, in the west 



