62 EIGHTH PACIFIC SCIENCE CONGRESS 



23, 1952; Yoshida, Kajiura and Hidaka, ROWJ, 1, 1953; K. Sato, HB, 

 16, 1950; HB, 25, 1951; Miyazaki, KS, 28, 1950; I. Kimura, CKH, 1, 1949; 

 H. Yamada, FE, 5, 1949; T. Ichiye, KH, 2, 1951; H. Hikada et al, KH, 

 1, 1949). To locate and track the storm or typhoon over the ocean, 

 studies of microseisms in relation to the ocean waves have been con- 

 tinued in the Earthquake Research Institute and in the Central Meteor- 

 ological Observatory. (F. Kishinoue, ERIB, 29, 1951, 277-282.) Studies 

 of beach erosion problems have been made with particular activities, 

 under the cooperation of various research groups. Experimental stu- 

 dies of surf in a model tank which were made by T. Haraada have 

 made an important contribution to this field. (Transportation Tech- 

 nical Research Institute, Report No. 2, 1951, 1-165.) 



Theoretical studies of wind waves have been made by K. Yoshida. 

 He pointed out the importance of the process concerning the mutual 

 exchange of momentum between ocean waves and ocean currents (K. 

 Yoshida, JOSJ, 7, 1951, 99-104). He suggested that energy transmitted 

 from wind to water goes partly into waves and partly into currents, 

 and furthermore, energy is transferred from shorter waves to longer 

 waves and also from waves to currents, mainly due to semi-irregular 

 breaking of waves. Based on a physical consideration, he derived an 

 equation to find an energy portion required to increase wave height and 

 wave velocity respectively, and therefrom an equation of wave growth 

 which slightly differs from Sverdrup-Munk's (K. Yoshida, GN, 4, 1951). 

 Energy distribution in wave spectra, which results from his theory of 

 energy transfer from shorter waves to longer waves, was compared with 

 actual wave data (K. Yoshida, JOSJ, 7, 1951, 49-54). Based on nonlinear 

 equations of waves with continuous spectrum, he suggested that the 

 frequent occurrence of waves of several minutes' period, surf beats, may 

 be ascribed to the general structure of the ocean wave spectrum (K. 

 Yoshida, GN, 3, 1950). Periods of surf beats are estimated approxi- 



mately from an original spectrum; T = where T denotes a period of 



energy maximum, and AT is the range of periods of wave components 

 with a significant amount of energy. M. Nakano published a paper in 

 1949, Yoshida attempted to find a modification of swell in shallow wa- 

 ter, where a bottom slope is not gentle enough to allow an ordinary 

 refraction diagram approximation to be valid (K. Yoshida, GN, 3, 

 1950). However, available wave records have not been sufficient to 

 prove and support these theories so far. 



An electrical recorder of waves was devised by S. Ishiguro, a very 

 able hydrographic mechanician. He constructed several types of wave 

 recorders and an apparatus for the stroboscopic analysis for preparing 

 the wave spectrum (S. Ishiguro, OM, 1, 1949; KK, 3, 1949; KK, 4, 



