Numerical study of the daytime urban effect and its interaction with the sea breeze

Abstract

Under light gradient-wind conditions, the heat-island effect associated with large urban areas is characterized by a temperature rise after sunrise over the land (ΔθL) and a temperature difference between the urban and rural areas (Δθ) during the day, whereas by only Δθ during the night. A daytime circulation can develop that is much stronger than the nocturnal circulation in spite of a generally smaller value of Δθ. The circulation decays under the influence of a moderate gradient wind. On the other hand, it persists in the sea-breeze system, and has a notable effect on the sea-breeze pattern. Some characteristics of the sea breeze observed in the Tokyo metropolitan area, such as formation of a suburban stagnant region, frontal intensification, and the delay of its advance inland, were well simulated with the simplified model. -from Author