2008 Volume 64 Issue 4 Pages 281-288
The cooling effect of urban green area on the surrounding area has been studied by many researches. Some studies observed seeping-out phenomenon or park breeze where the cooled air in the park flows outward to all direction of urban area. But there have been few studies on the movement of cooled air inside the urban green area when of seeping out phenomenon occur. In this study, we analyzed the movement of cooled air inside the urban green area at calm night and the relation with the seeping out phenomenon. Measurements were done during 23rd, 26th and 27th, July 2002 in Shinjuku-Gyoen Park. Thermocouples were set in 200 m lines with the interval of 20 m. We called these thermocouples as thermocouple array and three thermocouple arrays were set in the park. Two supersonic anemometers were used to measure wind velocity at the north and south edge of the park to detect the seeping out flow. In the analysis, the movement of cooled air was calculated by using cross correlation between pattern where temperatures decrease more than 1 K in 10seconds during 120seconds. We chose the points that indicated high cross correlation value more than 0.75 to calculate the velocity of cooled air. Most of velocities of the movement were between 0.1 m/s and 0.2 m/s at all points. At the south part of the park, the movement was measured most frequently. Velocity of the cooled air movement was smaller than the wind velocity measured by supersonic anemometers. Cooled air movements were not observed when the wind velocity was more than 1 m/s.
