Pasquill\u27s Stability in Nagasaki City from 1978 to 1980

Pasquill\u27s stability in Nagasaki City has been investigated for the period from 1978 to 1980. Pasquill\u27s stability during the night was estimated from the radiation balance at the ground. Meteorological data used in this study were those at Nagasaki Prefectural Government (wind) and Mt. Inasa (radiation) for 1978, and at Nishi-Urakami Branch of Nagasaki City Office (wind) and Nagasaki University (radiation) for 1979 to 1980. The distribution of Pasquill\u27s stability ranks considerably varies from year to year because of seasonal fluctuation of local climat. The strongly unstable condltion (A～B) at daytime is most predominant in early autumn (Sep. and Oct.) and the stable condition (G) during the night is also significant in autumnal period. These are because that fair weathers are brought from travelling anticyclones from the continent. Consequently, the most serious condition relating to air pollution would be taken place in late autumn. The largest proportion of neutral state (D) during both day and night appears in winter. The present results strongly suggest that the measurements of wind speed and direction over the complicated topography such as Nagasaki City should be made with special care