The Relationship between Urban Surface Indices and Heat Islands in High and Low Building Areas

Abstract

During 2003, temperature distributions were observed 69 times in two types of residential areas in Imaihara, Nagano Prefecture, Japan. Both high and low building areas were warmer than the rural area at night. But a cool island appeared only in the high building area in the daytime. The maximum nocturnal heat island intensity occurred not at a calm condition but at the wind speed of about 1 m/s. In addition the wind speed in which the maximum heat island occurred in the high building area was larger than that in the low building area. The urban surface indices of the high and low building areas showed only small differences in the sky view factor and building/ land ratio but large differences in the floor-area ratio. Floor area ratio related to heat island formation in this area.