Effects of urbanization and groundwater flow on subsurface temperature in three megacities in Japan

Subsurface temperatures were used to evaluate the effects of both urbanization and groundwater flow in three megacities in Japan. The magnitude of the heat island and time of the start of urbanization are preserved in subsurface temperature, and these signatures are clarified by meteorological data from these three cities. Heat conduction-convection analyses of subsurface temperature under the conditions of surface warming show that the ranges of the subsurface temperature indicate the magnitude of the regional groundwater flow in these three megacities in Japan.