Three kinds of field observation of urban thermal environment were carried out to examine the cooling effects of a river. One is the measurement on four streets across the river. Three measurement points are set on each street, one is on the bridge and the others are in the area of about 100m from the river. These streets are selected along the river within 7km upstream from the coast. This is called Obs.1. Another is the measurement along a river and an avenue which go in the direction of the sea-land breeze. They are nealy parallel in the dountown with the distance of about 400m and cross each other at 7km upstream from the coast. Measurement points are set on the coast and the cross point. Moreover, there are four measurement points each on the river and on the avenue scattered between the coast and the cross point. This is called Obs.2. Another is the measurement along a street nealy perpendicular to the river. There are also ten points in the area of about 800m from the river. This is called Obs.3. The measurement points of Obs.1 and Obs.3 are grouped into 3 types, one is above the river, another is at the cross point with the other paths and another is in the cavity of buildings. The air temperature above the river is the lowest and next at the cross point where the wind direction is close to that of the sea breeze. It indicates that even small paths have ventilation effect on urban thermal environment. The results of Obs.2 show that the air temperature above the rever is clealy lower than that above the avenue when the sea breeze blows. The air temperature difference between them falls smaller in the downstream of the sea breeze. It is possible that the sea breeze mitigates the heat in the urban area, if it is well designed to utilize the sea breeze.
