Abstract
Effects of both natural topography in various scales and change of land-use on wind and temperature fields have been investigated numerically for Nohbi plain, central Japan. It has been clarified that, in spite of highly urbanized nature of Nohbi plain, shown in a large population of more than 8 millions, basic features of local winds over the plain are determined by natural topography, especially high mountains in Chubu district, which are located 100 to 200 km north-east to the plain.
However, temperature fields at surface level can largely be modified by urban area and also water surface such as rice paddy fields. An explanation for high temperature zone caused by urban area in sea breeze situation is presented. Urban area, i. e. a local heat source, placed in the topographically induced sea breeze/valley wind causes weak wind zone at down-wind side of the area due to pressure gradient adverse to the sea breeze. In the weak-wind zone, mixed layer strongly develops and “heat island” is formed. The “heat island” moves inland with the sea breeze.
