日本各地に於ける最高氣温最低氣温の逐年變化

Abstract

This short note is essentially a sequel to one which the author published recently in this journal(1). Annual values of mean daily maximum (or minimum) temperature at 20 stations are carefully calculated and analysed by means of the Method of Least Square. Assuming Θ=Θ0+b1t, or θ=θ0+b2t, where Θ or θ is the every year means of mean daily maximum or minimum temperature, t the time whose unit is one year. The four constants Θ0, θ0, b1 and b2 are determined by the well-known process. If b1 is positive, then the local mean daily maximum temperature is tending to increase year after year, and if b2 is negative, then the local maximum temperature is tending to decrease. The analysed results are shown in Table 1. In Table 1, we find that in large, developing cities such as Tokyo and Oosaka, the mean daily maximum temperature is almost invariable while the mean daily minimum temperature is tending to increase year after year with relatively large increasing rate. The increasing rate of mean daily minimum temperature is 2.6°C per one century at Oosaka and about 1.5°C per one century at Tokyo. The causes of these phenomena are probably due to both artificial generation of heat and atmospheric pollution.