1977 年 12 巻 8-9 号 p. 449-455
According to Taylor's theory, plume width is estimated from the standard deviation of integrated horizontal and vertical components of wind speed. Estimated crosswind width of plume by this method and other five methods are compared with the values measured at the Kawaguchi Tower between 250 and 6, 000 m downwind distance from the source. The source height of the diffusion experiment is 45 or 313 m and sampling duration is 20 or 30 minutes. In the unstable and neutral conditions the maximum correlation is obtained between the values estimated by present method and measured values. In this method, mean of ratios of the estimated values to measured ones is 1.04, and the deviation of estimated values from measured values is minimum. In other five method, mean value of the ratios are as follows: Singer and Smith's: 1.20, Singer, Frizzola and Smith's: 1.44, Yamamoto and Yokoyama's: 1.52, Pasquill, Gifford and Slade's: 0.63, and Pasquill and Gifford's 0.64. In stable conditions, because of large vertical shear of wind speeds, the estimated values derived from wind at source height are smaller than measured values, and the ratio of estimated and measured values is in inverse proportion to vertical shear of wind speeds.