ON THE OCEANOGRAPHICAL CONDITIONS OF THE SEA 



NEAR THE FIXED POINT, 153°E, 39°N, IN THE 



NORTH PACIFIC OCEAN 



By M. Nakano, M. Koizumi and J. Fukloka 



Central Meteorological Observatory of Japav, Tokyo, Japan 



1. Introduction 



The variations of water temperature, chlorinity, etc. in deep layers 

 oi the ocean have not yet been made clear owing to the scarcity of con- 

 tinuous data of serial oceanographical observations taken at a fixed 

 point for a long time. However, several years ago, ocean weather sta- 

 tions were set up, and serial oceanographical observations are being 

 made without interruption. 



In Japan, the first ocean weather station was established at the point 

 153°E, 39°N, in the North Pacific Ocean, in October 1947, and the 

 second one at the point 135'^E, 29°N, in June 1949. The former station 

 is now named "Extra," and the latter "Tango." The data of meteoro- 

 logical and oceanographical observations at these fixed points are pub- 

 lisiied in "The Results of Marine Meteorological and Oceanographical 

 Obsei~uations," a quarterly bulletin of the Central Meteorological Ob- 

 servatory of Japan. 



At these fixed points oceanographical observations are usually made 

 from surface to a depth of about 1200 ra. about 12-24 times a month, 

 the main oceanographical elements observed being uater temperature, 

 chlorinity, and contents of oxygen and plankton. In the present paper 

 the authors intend to report some results of investigation on the varia- 

 tions of water temperature and chlorinity in deep layers mainly, together 

 with some other results, made from the data of observation at the fixed 

 point "Extra" (Fig. 1). 



2. W.-VTER Temperature 



(a) The annual variation of water temperature, hi the first place, 

 the authors calculated the monthly mean water temperature of each 

 layer. Figure 2 shows the variations thus obtained of water tempera- 

 ture of the layers m. (surface), 25 m., 50 m., 100 m., 200 m., 300 m., 

 400 m., 500 m., 800 m., 1000 m. and 1500 m. From this figure we can 

 see that the water temperature near the surface becomes minimum in 

 February or March and maximum in August or September and that. 



