やまじ風発生時の気象状況について(1) : 統計的特徴

概要

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The local severe wind "Yamaji-kaze" occurs over the coastal area of the eastern part of Ehime Prefecture. The Yamaji-kaze is a southerly downslope wind rushing from the ridge of the Shikoku Mountains. The characteristics of the Yamaji-kaze have been investigated. During the early stage of the Yamaji-kaze, the wind direction and wind speed vary widely. The gust factor is ranging from 2 to 4. After the onset of the mature stage of the Yamaji-kaze, fluctuations of wind direction decrease rapidly and the gust factor becomes about 2.2 at this stage. Climatological investigations show that the Yamaji-kaze occurs fourteen times a year on average and the very strong one occurs twice a year. The Yamaji-kaze occurs mainly within a period from March to June. The Yamaji-kaze is caused by extratropical cyclones and typhoons and the percentage occurrences are 85% and 15%, respectively. The Yamaji-kaze caused by typhoons occurs in July to September.
2008-10-31