首都圏における夏期の降水特性の経年変化

概要

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Local heavy rainfall events often occur in the Baiu and midsummer seasons in Japan. These rainfall events sometimes cause severe disasters, not only in the rural areas, but also in the urban areas. Some authors mention that global and local climate changes may cause long-term changes in the frequency of heavy rainfall events. In the present study, changes in the properties of summer precipitation over 23 years(1976-1998)in the Tokyo area were examined, by using AMeDAS(Automated Meteorological Data Acquisition System)data. Our results show that the ratio of heavy precipitation to the total amount has increased in the Tokyo area in August, although the total amount itself has not changed significantly. The changes in the ratio are highly localized, and cannot be seen during the other periods of the year. The mean temperature has increased in the center of the Tokyo area, corresponding to the changes in the precipitation properties. Further analyses of the AMeDAS wind data show stronger convergence of the horizontal wind in recent years. From these results, it can be reduced that the changes in the precipitation properties may have been caused by stronger cumulus convection over the urban area in 1990s resulted from the strengthening of the heat island.
社団法人日本気象学会の論文
2000-09-30