Urban and Green Planning Based on an Evaluation of Urban Climate
Global warming and the increased prevalence of heat islands are seriously undermining human health in metropolitan areas. An appropriate adaptation strategy is needed to address these effects. In this study, we have simulated thermal and wind environments using a supercomputer, and clarified the dominant factors behind the rising temperature by comparing the thermal and wind environments of two periods: the Meiji Period (1884) and the recent past (2006) using geographic information software. The simulation area is 7.5 km × 7.5 km and 400 m in height with a mesh resolution of five meters. The simulation model simultaneously handles flows of wind in the upper boundary layer and the microclimate in the canopy layer, in which the heat exchange of different layers actively occurs at an altitude of 50–100 m above ground level. The model provides statistical clarification of the dominant factors behind the rise of temperature and changes in wind velocity between the two periods. Regression analysis was conducted, in which the change of land cover on the microtopography and the change of wind flow in the upper layer were set as independent variables. The change of temperature and wind velocity in the canopy layer were set as explained variables. Results show how the changing green space and buildings influence the temperature rise in hierarchical scales. Effective indicators and metrics were devised and applied to inform the next step, which is to devise adaptation strategies to climate change that take account of future changes in land use.