Comparison of Temperature Increases with Urban Surface Cover for Different Geographical Conditions in Japan

In order to reveal the relationships between physical-geographical conditions and temperature rises in cities, the dependence of the rate of surface air temperature rise on urban surface cover was compared for different physical-geographical conditions for cities in Japan. The monthly mean temperatures observed in 74 sites selected to fulfill specific criteria from 1964 to 2011 and land use data categorized into 11 types, at 100 m spatial resolution, including buildings and roads, were used. The rate of the monthly mean of the daily mean temperature rise for the coastal sites has a positive correlation with the distance from the coastline. The rate of temperature rise was found to be positively correlated with an urban cover index for the coastal observation sites within 7 km from the coastline, and for the sites including the coastal sites more than 7 km away from the coastline and the inland sites. The change in the rate of temperature rise with respect to the urban cover index is higher for the inland sites than for the coastal sites within 7 km of the coast. The largest difference in the rates is shown in winter. The rate of temperature rise at sites more than 7 km away from the coast is similar to those at inland sites. The study has implications for predicting future changes in cities and the greater vulnerability of inland cities to enhanced warming.