Prediction of Air Temperature Distribution in Urbanized Area of Tokyo, Japan Using Airborne Themal Images

This study presents a method used for predicting the air temperature distribution in an urbanized area from the surface temperature of trees. A strong trend of urbanization can be observed whole over the world (United Nations Centre for Human Settlement, 1996). It is well known and documented that urbanization can have significant effects on local weather and climate (Landsberg, 1981). One of these effects is the urban heat island, for which the temperatures of the central urban locations are several degrees higher than those of nearby rural areas of similar elevation. The urban heat island effect has been the subject of numerous studies in recent decades and is exhibited by many major cities around the world. In order to establish a countermeasure against the urban heat island, it is necessary to understand the feature of the thermal environment, especially, the distribution of air temperature. It is, however, difficult to know the distribution of air temperature for large area through the field measurements. The method to provide the information on the distribution of air temperature for a large area or region would need to be developed for the establishment of sound environmental planning to improve the thermal condition in cities. It is well stated and reported that the surface temperature of tree is strongly correlated with the ambient air temperature. Using this feature, Murakami (2009) generated air temperature distribution map for a local small city in Japan. The study, however, was implemented in the region where the influences of long wave radiation from the surrounding buildings on the surface temperature of trees could be omitted. In this study, the objective was set to examine the possibility to apply the method developed in Murakami (2009) to highly urbanized area, to acquire the air temperature map of Tokyo through the proposed method, and to discuss the thermal environment of Tokyo using the map.