Y. Matsudaira discussed in the same year the influence of hydrographic 

 conditions of the North Pacific upon the cHmate of Japan and tried the 

 long-range forecasting. In the same year Yukimasa Saito published a 

 short note on the tidal currents in the Fukuoka Bay. 



In 1943 Uda discussed the accuracy of the ocean ographical observa- 

 tions in this country. He also discussed the fusion of icebergs rather 

 theoretically. Yasui examined the annual rise and faU of the sea-level 

 in the Inland Sea derived from the variation of density. He also made 

 several in^'estigations on the scales of ocean waves and winds over the 

 sea. In the same year Uda and H. Arakawa discussed the relation 

 between hydrographic conditions and movement of depressions near 

 Japan. 



In the fall of 1943 Uda was called for military service, and Dr. T. 

 Sano succeeded him as the Director. Sano, who was a meteorologist, 

 made little contribution to oceanography. He died prior to taking up 

 his duties in March, 1945, and Yasuo Matsudaira succeeded to the 

 directorship. 



In 1944 Z. Yasui published two papers on the tidal currents and 

 the manoeuvring of ships. In the same year Yukimasa Saito published 

 an important paper on the calculation of vertical stability in the sea 

 from the dynamical consideration starting from Lagrangian equations. 

 The results of computation are practically unaltered, but the process is 

 much simpler than the older one. He also published a theory of evapora- 

 tion from the surface of the sea, and that of the stability oscillations of 

 water in the sea. 



Recently Saito completed an extensive theoretical research on 

 Oyashio, or the Kurile Current,, partly consisting of water mass anaylsis, 

 He also solved the differential equation giving the simultaneous effect 

 of both horizontal and vertical mixing and showed that at a great distance 

 from the sources the horizontal mixing could be neglected. 



T. Itiye, who, too, works in this observatory, is also a very eminent 

 young hydrodynamician, completed a new theory of tsunami waves in 

 1948. He attributes the tsunami to a non-stationary disturbance. 



Itiye also showed that when a solitary wave propagating through a 

 uniform channel passes by a narrower part it is divided into a train of 

 waves. 



Activities of the Central Meteorological Observatory and 

 Marine Observatories 



The Marine Section of the Central Meteorological Observatory 

 was opened in 1942, the first chief being K. Tsukada, who was afterwards 

 succeeded in 1944 by K. Hidaka, Professor of Phj'sical Oceanograph}' 

 of the Tokyo University. He has been a concurrent member since he 

 was transferred from Kobe in 1942. 



Prior to this period we have some contributions in this Observatory. 

 In 1941 M. Hayakawa, of the Osaka Meteorological Observatory, 

 published a series of results of model experiments on tsunami and ocean 

 waves. In 1942 H. Arakawa, of the Central Meteorological Observatory, 

 discussed the short-period irregularities observed in the water temperature 

 in lakes and seas, ascribing their origin to the stability oscillations of 

 water layers as suggested by T. Hesselberg some ten years before. 



198 



