Departmental Bulletin Paper 我が国における降水特性の長期変化と極端降水量の増加
Long-term Variation in Precipitation and Increase in its Extreme in Japan

田中, 茂信

It is important to know current situation of hydrological condition including its tendency for effective water-related disaster risk management. This study investigates trend and extreme characteristics of recent precipitation in Japan with AMS(Annual Maximum Series) and POT(Peaks Over Threshold(100mm)) at 155 meteorological observatories. It shows that most rainfall stations show slight decrease trend in annual precipitation but slight increase in annual maximum daily precipitation. Average of all rainfall stations in Japan is in significantly increasing trend. Events exceeding 100mm/day is significantly increasing in 1901-2014 while 1940-2014 is in just slight increase. Even in 1940-2014, the largest 50th rainfall in Japan shows significant and steady increase. These results show the importance of POT analysis not only AMS data. The advantage of this method would be with not only observation data but GCM data.

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