Numerical study on the effect of buildings on temperature variation in urban and suburban areas in Tokyo

A numerical investigation of the temperature variation in urban and suburban areas due to the presence of buildings was carried out using a one-dimensional canopy model combined with a meso-scale meteorological model. Since temperature increases in an urban area are caused by sensible heat from building surfaces besides anthropogenic heat and reduction of wind speed due to buildings' drag, we estimated each cause separately to determine the contribution by each to the temperature variation. The simulation was performed for. Kanda, an urban area, and for Nerima, a suburban area of Tokyo. Comparisons were made with actual temperatures before the estimation. The comparison indicated that the measured temperatures in the Kanda and Nerima areas were nearly reproduced by the model. The sensitivity analysis indicated that, in a comparison with the temperature in no building environment, the contribution of (i) sensible heat flux from building surfaces to temperature rise was 49% in Kanda and 20% in Nerima, (ii) wind reduction due to drag was 41% in Kanda and 59% in Nerima, and (iii) the effect of the interaction between (I) and (II) was +10% in Kanda and +20% in Nerima.