Since the unusually hot summer in 1994, extremely high temperatures have frequently been observed in the midsummer season in Japan. As a possible factor increasing the heat, the urban heat island effect has received public interest, calling for political and technical measures to alleviate it. However, it still remains uncertain whether and how the urban effect contributes to the recent heat. The present paper aims to describe the spatial distribution and trends of high temperature with attention to urban anomalies using the data of the Automated Meteorological Data Acquisition System (AMeDAS) network.
The analysis of the spatial distribution of high temperature is based on daily maximum and minimum temperatures (T_max and T_min) defined from 10-minute data for the period 1994-2002. The daytime high temperature (T_max_??_35°C, T_max_??_38°C, and the annual extreme of T_max) was the most pronounced in the inland part of three large urban complexes centered on Tokyo, Osaka, and Nagoya. The nocturnal high temperature (T_min_??_25°C and T_min_??_28°C) was pronounced at coastal stations and in large cities, especially in Osaka and Tokyo. These features are apparently in agreement with previous studies on the urban heat island, which is characterized by nocturnal warming in the central area of cities and daytime warming on the inland side of large urban complexes located on the coast.
To evaluate the trend of high temperature in recent decades, the ten highest values of T_max and T_min in each year and their deviation from the 850-hPa temperature were analyzed using hourly data from 1979 to 2002. There were rising trends in T_max and T_min on the order of 1°C/(20 years) in a wide area from central Honshu to Kyushu. The change at 850 hPa accounts for only a fraction of these changes. These facts indicate rapid warming in the background field during the past few decades, with a larger amplitude in the boundary layer than in the free atmosphere. The signal of urban warming is nearly concealed in this change, but there are some anomalous trends of T_max in the inland areas adjacent to the three cities by 0.2-0.4°C/(20 years) in comparison with surrounding regions. This implies the existence of slowly intensifying urban warming, which can have a substantial impact on a time scale of several decades or a hundred years.
In conclusion, the frequent occurrence of extremely high temperature in the major urban areas in Japan can be attributed to the rapid background warming in the past few decades superimposed on the preexisting and slowly intensifying urban heat island.

View full abstract

This article examines the relation between the contemporary urban environment and disability as a deprivation of life implementation of persons with physical impairments, through a survey of actions by which persons with lower-limb impairment secure access to various activity opportunities within the early developed area of Tama New Town, Tokyo, Japan. The results of qualitative and quantitative analyses are presented below.
Persons with lower-limb impairment who were interviewed in this study uniformly perceived steep slopes and stairs in staircase-style apartments and other buildings as barriers to their activities. Those who suffered impairment of limb functions after moving to the study area, in particular, experienced a shift in their perception of the built environment, from a safe and comfortable environment while they were of sound body, to a barrier after experiencing physical impairment. This experience suggests that Tama New Town is an urban space designed for able-bodied people.
While living in an urban space full of barriers, the surveyed individuals have restructured their life space to enable going out by 1) restructuring the relation between physical abilities and the environment by improving the built environment (change of home and barrier-free implementation) and utilizing effective ambulatory aids and means of transport (motorized ambulatory aids and personal cars); and 2) accepting the assistance of others. However, the validity of these actions is conditioned by the ownership of fixed property and goods, the stages of family life cycle and social network development, and the embodied knowledge and information about living in that area.
In the study area, to enable a home entry/exit in a medium-rise, staircase-style apartment forces people into moving from the current living area, with a high likelihood of rending useless existing resources that contribute to an enabling life space, such as the social network and knowledge. This is due to the fact that there is no assurance of relocation within the same neighborhood. However, continuing to live in their current home also means the continuation of barriers to home entry/exit. In the fragmented life space that results if such a dilemma cannot be resolved, persons with physical impairment are likely to be deprived of their life implementation.

View full abstract