REPORT ON OCEANOGRAPHY 63 



1950; K. Sato, HB, 15, 1949). Wave recorders of pressure type have 

 been installed at several parts of our coasts, and especially continuous 

 records at Yogashima Island have been analyzed by the staff of the 

 Oceanographic Section of the Central Meteorological Observatory (M. 

 Nakano, S. Unoki and Y. Kuge, OM, 5, 1953, in press). The accumu- 

 lation of such data as well as activities of the staff may afford a pro- 

 mise of progress in forecasting. One of the most successful and interest- 

 ing results from the wave recorders installed by this staff is that a re- 

 corder at Hachijo Island recorded long sea waves (tsunamis) produced 

 by an eruption of a submarine volcano in September of 1952, and that 

 S. Unoki and M. Nakano could explain the observed change of period 

 and district beat phenomena by solving the wave problem of Cauchy- 

 Poisson type (S. Unoki and M. Nakano, OM, 4, 1952; OM, 5, 1953). 

 This record at the station 130 km. distant from the volcano showed 

 that the period decreases gradually with the lapse of time, from 95 sec 

 to 30 sec, and also showed distinct beat pattern. A stereophotogram- 

 metric study of the surface was atempted by K. Sato, who was lost on 

 board the wrecked vessel at the eruption of the Myojin volcano. 



In 1951 and 1952, Masamori Miyazaki published papers on math- 

 ematical studies of surf and breakers in water of constant slope (Masa- 

 mori Miyazaki, OM, 3, 1951; OM, 4, 1952). He also discussed the wind 

 stress over the wavy sea surface mathematically (OM, 3, 1951). A prob- 

 lem of "tidal race" was taken up by Miyazaki in 1949 and by T. Ichiye 

 in 1951 (Ichiye, OM, 1, 1949; Miyazaki, OM, 1, 1949). K. Hidaka 

 published two papers of surface waves in 1951. He proposed a very 

 simple explanation as to why the group velocity is equal to the velocity 

 with which we can follow the waves without change of wavelength 

 (K. Hidaka, JOSJ, 7, 1951). Hidaka and A. Nakano calculated the sur- 

 face profile of high waves from Stokes' equation by means of numeri- 

 cal calculations instead of successive approximation procedures (Hi- 

 daka and A. Nakano, JOSJ, 7, 1951). 



Storm Tides 



Ariake Sea, which is a shallow water in the island studded part in 

 western Kyushu, has a big productivity. This area is much frequented 

 by typhoons. A computation was made by K. Terada as to how high 

 the storm tides accompanying the passage of typhoons would be. A 

 theory for such a phenomenon had been established by several persons 

 immediately after the "Muroto" Typhoon which caused serious dam- 

 age in the heart of Japan by a heavy storm tide in 1934. Masamori 

 Miyazaki is one of those who recently solved the problem of storm 

 tides caused by a travelling storm in an infinite and semi-infinite seas 

 (OM, 4, 1952, 1-12). 



