Abstract
Change of environment over the ground have influenced upon soil temperature in urban area. According to the data measured by Tokyo district meteorological observatory in midtown area, the yearly mean soil temperature is rising gradually, for example it increased by 2.0℃ at a depth of 1. 2 m and 1.5℃ at a depth of 3.0 m from 1923 to 1950. The range of yearly change in soil temperature tends to increase, for example it increased by 2.0℃ from 1928 to 1946. We measured soil temperatures at depths of 0.5 m and 1.0 m at 68 points in urban area and suburb area through the year (from July in 1982 to July in 1983). Air temperature in midtown area was higher than that in suburb area by 5℃ at night on a winter day and heat island grew conspicuously at this time period in midtown area. But in summer the average soil temperatures at depths of 0. 5 m and 1.0 m of 19 points in 4 km square in midtown area (A area in Fig. 5) are higher than those of 25 points in 2 km square in suburb (B area in Fig. 5) by 2.0℃, and in winter there are little difference between the average soil temperatures in both areas. Also in summer, the average soil temperatures at depths of 0. 5 m and 1.0 m of 24 points in 25 km square in the 23 Wards area (C area in Fig. 5) are higher than those in suburb area (B area in Fig. 5) by 1℃.
