THEORETICAL ANALYSIS OF THE EFFECT OF MEAN WIND AND STABILITY ON A HEAT ISLAND CIRCULATION CHARACTERISTIC OF AN URBAN COMPLEX

Abstract

A simple two-dimensional linear model was used to explore the nature of the heat island circulation of an urban area. Two stability categories, stable and near-neutral, were assumed to define the boundary layer conditions. The heat island circulation was studied under the condition of no-mean wind and also for cases when a mean wind existed. The forcing function (differential heating) was given as a smoothly varying function in the horizontal that would create a smoothly varying temperature field with no discontinuities in the temperature distribution. A rather weak two-cell circulation system was developed in which depth and intensity were dependent on the boundary layer stability. Allowing a mean wind to exist produced a displacement of the two-cell circulation downstream to a location that is a function of the heating rate and the advection of heat and momentum by the mean wind.