The effects of land-use and anthropogenic heating on the surface temperature in the Tokyo Metropolitan area: A numerical experiment

Abstract

In order to investigate the effects of land-use and anthropogenically produced heat on the surface air temperature in the Tokyo Metropolitan area, numerical experiments were carried out under typical summer synoptic conditions. The model is based on the three-dimensional Boussinesq equations, taking into account the hydrostatic assumption. Since land-use differs over every subdivision in Tokyo, the model includes a sub-grid parametrization scheme which can calculate the total heat flux a grid surface composed of different surfaces. The diurnal variation of the simulated surface air temperature agrees well with the observed value; an average over 36 days which represent typical summer days; i.e. negligible gradient winds and almost clear skies. The model shows that the contribution of anthropogenic heat is much larger at night, in spite of the lower energy consumption as compared to daytime use. Due to the scarcity of green vegetated areas in the central part of the city, the surface air temperature is enhanced in this region during daytime, however this enhancement is small after midnight.