都市熱環境における植物の役割に関する研究

SiBモデルに基づく数値シミュレーション

抄録

Thermal environment of urban areas is largely determined by the physical structure of their land surface. Green tracts, in particular, play an important role in the heat balance through evapotranspiration. In order to quan tify the role of urban vegetation in the determination of surface temperature, this study conducts numerical simulations based on Simple Biosphere model (SiB) and analyzes the relationship between physical peculiarities of vegetated land surface and temperature distribution. SiB was originally developed for GCMs, in order to calculate the transfer of energy, mass and momentum between the atmosphere and the vegetated surface of the earth. The vegetation in each terrestrial model grid area is represented by two distinct layers. The upper layer represents the perennial canopy of trees or shrubs, and the lower layer represents the annual ground cover of grasses. SiB contains three temperature-related variables, each of which represents the temperatures of different components of the ground surface; i. e., canopy, ground cover and the air space in can opy. Thus the variation of temperatures at different parts of the vegetated ground surface is analyzed and the calculated values are compared with the the brightness temperature measured by remote sensing.