Numerical Experiments of the Land and Sea Breeze Circulation

Abstract

An effect of the urban heat island o n modification of the land and sea breeze circulation was discussed by making a differential diurnal temperature change between urban and suburban areas. Here a two dimensional numerical model was applied, and the following assumption was used: higher daily mean temperature and smaller diurnal change in urban area and colder mean temperature and larger diurnal change in suburban area. Under these conditions invasion of sea breeze was slowed down and land breeze was intensified. Double vertical circulation cells were formed; one was around the coastline and another along the border between the urban and suburban areas. A three-dimensional experiment of the land and sea breeze circulation over the Kanto district of Japan was integrated in a domain of 204 km × 204 km × 1.8 km for two simulated days. In this experiment the actual coastline was outlined in the grid of 6 km meshpoint interval, and a uniform diurnal temperature change was assumed on the land area. The computed land breeze and sea breeze were converged or diverged according to a concave or convex coastline. Internal gravity oscillations were found in the front of sea breeze.