REPORT ON OCEANOGRAPHY 49 



effect of inland water can be seen in the region several kilometers off 

 this island (ROWJ, I, 1953). 



Energy Exchange Between the Sea and Atmosphere 



In 1949 Michio Miyazaki made an attempt to estimate the heat 

 budget in the Tsushima Current flowing along the Japanese coast of 

 the Japan Sea. He assumed that the gain and loss of heat per day 

 at the sea surface in this warm current can be calculated by the balance 

 of incoming solar radiation, radiation from the earth, evaporation and 

 cooling by convection. He obtained the results that the net loss of 

 heat from the sea surface by terrestrial radiation is nearly constant 

 throughout the year, that the rate of evaporation and the cooling by 

 convection is greater in winter and smaller in summer and that the 

 annual net gain by the sea is negative, showing that the heat is trans- 

 ported by the current (OM, 1, 1949, 103-111). He also applied the 

 same computation to the entire Japan Sea, dividing this sea into 2-de- 

 gree squares, and discussed the heat budget, formation of water masses, 

 transportation of heat by currents (HFLB, 4, 1952, 1-54). A similar 

 attempt was made by K. Terada and T. Osawa for some areas in the 

 adjacent seas of Japan (GM, 24, 1953, 155-170). T. Ichiye also showed 

 that the annual thermal cycle in the Osakawan cannot be explained 

 by the evaporation and radiation from the water inside the bay, but 

 that we must take into account the heat entering from outside the bay 

 by horizontal diffusion (JOS J, 6, 1950). 



A similar estimate of the heat exchange between the atmosphere 

 and the sea was made by J. Masuzawa based on the weather ship ob- 

 servations at a station 29°N, 135°E (OM 4, 1952, 49-55). 



M. Hanzawa followed Sverdrup and Jacobs in estimating the eva- 

 poration from the sea surface based on weather ship observations at two 

 stations close to the Japanese Islands. He found that in the North 

 Pacific the maximum evaporation takes place in winter months and 

 it is in a minimum in early summer. He compared the result with G. 

 Wust's (OM, 2, 1950, 77-82). 



Oceanographic Optics 



Since several years ago T. Takenouti has studied submarine illu- 

 mination in seas and lakes. He defined as "diffusion-ratio" the ratio of 

 the illumination by the light from above over that coming from below. 

 He showed theoretically that this ratio is independent of the depth of 

 the layer if the water is optically uniform and only varies when there 

 is a stratification of layers. He compared this with actual observa- 

 tions successfully. He found that hitherto debated variation in the 

 characteristics of this layer has all depended on the discontinuous layer 



