REPORT ON OCEANOGRAPHY 51 



Fukutomi made extensive studies on the formation and growth of 

 the ice crystals in sea ice, salinity and physical measurement of strength, 

 microscopic inspection of the structure of sea ice, prediction and the 

 growth of ice in the central part of the Okhotsk Sea. He also found 

 that there is a turbulent layer of about 40 m. thick on the surface of the 

 Okhotsk Sea. He established a theory of formation and growth of sea 

 ice and applied it to this area and could predict when the ice is formed 

 in this area, and how it grows. He also tried to estimate by simple 

 empirical formulas the dates at which the air temperature over the 

 sea reaches the freezing point of sea water. He made an extensive 

 survey of ice along the north coasts of Hokkaido Island and discussed 

 how the temperature distribution varies with the cycle of the atmo- 

 spheric temperature, and compared the result with theory. He mea- 

 sured the temperature and salinity in situ, and concluded that off the 

 northern coast of Hokkaido there exists a supercooling in the sea wa- 

 ter just below the lower surface of the ice. Fukutomi, Kusunoki, and 

 Tabata examined the wind drift of ice and recognized the influence 

 of the Earth's rotation showing a deviation from the direction of the 

 wind. They made experiments with a floating block of ice in a narrow 

 sea and applied the result on the ice drift off the northern coast of 

 Hokkaido. They also discussed theoretically how the stationary motion 

 of ice occurs when the surface of the sea is partially covered and com- 

 pared the result with those obtained by Nansen in the Arctic Sea dur- 

 ing the drift of the 'Tram" in 1893-96. Fukutomi and Kusunoki also 

 published a theory on the formation and structure of ice ridges. Fuku- 

 tomi, Saito and Kudo measured various physical properties and struc- 

 ture of the sea ice by photographic methods. Fukutomi gave a theory 

 for the approximate estimates of the thickness of sea ice in relation to 

 the average air temperature, and its annual range. Tabata tried a pre- 

 diction of the data at which a last tract of drift-ice can be seen in 

 the southern Okhotsk Sea coast of Hokkaido (TK, 3-9, 1950). 



Hydrography 



The hydrography of the East China Sea was discussed by M. Uda 

 and he made clear the seasonal variation of water temperature, salinity 

 and meteorological factors in the Yellow Sea and the East China Sea, 

 and showed that the fluctuation of the Kuroshio at the margin of the 

 continental shelf controls the intensity of the Tsushima Current. (Re- 

 port of the Seikaiku Regional Fisheries Laboratory, 1950). He also dis- 

 cussed the hydrographic fluctuations in the Japan Sea (Japan Sea Re- 

 gional Fisheries Laboratory Report, 1952). 



Hydrography in the Japan Sea during the spring and summer, 

 1949, has been reported by I. Yamanaka (JOSJ, 6, 1951; 1953, in press). 



