On the regional and seasonal characteristics of recent surface air temperature changes in Japan with considering urban climate effects

Abstract

To estimate the regional and seasonal characteristics of the secular change in surface air temperature (SAT) over the agricultural land of Japan, we firstly analyzed the urban climate effect involving 17 general meteorological observatories selected by the Japan Meteorological Agency, and secondly, newly defined 19 stations mainly located in rural areas of Japan as representative of Japanese agro-land (Rural-19). As following analyses for regional and seasonal changes of the SAT trends, SAT was found to increase remarkably in February throughout Japan and in July over East Japan, although slightly decreasing in August and December over North Japan. The averaged trend in terms of temperature increase in the Rural-19 for each month during the period 1980-2004 was estimated to be within the range 0.3-1.4°C of the daily minimum and 0.5-2.4°C of the daily maximum SATs, respectively. The trend of the maximum SAT shows remarkable regional and seasonal variations compared with that of the minimum SAT.