Seasonal Variation of the Temperature of Water of the Rivers in Japan

[摘要] The seasonal variation of the water temperature of 12 rivers in this country observed in 1931 and 1932 was examined. From the difference between the temperatures of water-and air the following three river-types are recognized.A. Lower type: The period in which the water-temperature is lower than the mean air temperature is limited only for 1 or 2 months of the summer and moreover the difference of both temperatures is below 2°C. (R. Kawadana at Nagasaki, R. Asahigawa at Okayama, R. Arakawa at Kumagaya and R. Kitakami at Isinomaki) B. Middle type: The period above mentioned is for 5 or 8 months of the warmer seasons and the difference is above 4°C. The minimum water-temperature occured in February. (R. Arakawa at Titibu, R. Kinugawa at Utunomiya, R. Tikumagawa and R. Saikawa at Nagano and R. Mogamigawa at Yamagata.) C. Upper type: The period is further widened to the almost all months of the year and the high period of water-temperature is only for 1 or 3 months of the winter. The difference of both temperatures is greater than that of the middle-type. (R. Hirosegawa at Maibasi and R. Susohanagawa at Nagano.)

[学科分类] 大气科学