Cooling effect of tokyo bay on "sultry nights" with calm wind conditions

In this study, the authors focused on light wind from the sea and its thermal environment relaxation effect during periods of calm conditions during the night when there is a concern that the urban heat island phenomenon is exacerbated. The light wind from the sea may be characteristic to urban waterfront areas where temperature increase persists throughout the day even during the night because of accumulated heat on the ground surface and artificial exhaust heat. The wind directions during periods of calm conditions at night were compared. The ratio of sea breeze to land wind near the ground level was greater than the ratio of the upper-level wind during calm conditions at night. The authors focused on the period when upper-level wind was calm. As the upper-level wind became calm, the wind direction changed from land breeze to sea breeze, and the temperature decreased as the direction of the wind changed. These observations indicated the temperature lowering effect of light wind from the sea. Previous studies of the wind system during the night generally discussed the land breeze. This study was unique in that the authors' focused on utilizing the cool light breeze from the sea at night.