Detailed structure of heat island phenomena from moving observations from electric tram-cars in Metropolitan Tokyo

In this study, the detailed horizontal structure, i.e. cliffs and plateaux of the heat island of the Metropolitan Tokyo area is investigated. According to Oke (1977), cliff is steep temperature gradient at the rural/urban boundary and plateau is a steady but weaker horizontal gradient of increasing temperature towards the city center. However, these features are not always evident, e.g. large city like Tokyo. To elucidate such aspects, moving observations of the horizontal distribution of air temperature from electric trains of the transportation network of Metropolitan Tokyo during late evening or early morning were thus conducted. In total, 16 railroad lines were used for the moving observations. The observations were done in two phases for sectional and horizontal distributions. Results show that three cliffs exist in the heat island of Metropolitan Tokyo, although the location of these cliffs should be taken into consideration for urban planning or urban redevelopment.