Stability classification by acoustic remote sensing

Abstract

Two different Doppler acoustic sounders have been operated at the Kernforschungszentrum Karlsruhe (KfK) since 1982. It has been investigated whether meteorological data from these sounders can be used for dispersion modeling and monitoring in the environment of pollutant-emitting plants. Data from the sounders and from a 200 m high meteorological tower have been sampled continuously for intercomparison. Two schemes of stability classification are presented. They are based on 30-min mean values of the following meteorological data measured by the acoustic sounders: (a) standard deviation σ w of the vertical wind speed and horizontal wind speed u, at a height of 100 m; and (b) standard deviation σ φ of the vertical wind direction at a height of 100 m and vertical profile of the backscattered amplitude A w. The class limits applied in these schemes are determined by “statistical equivalence” with a standard classification scheme. This standard scheme is based on σ φ , measured by a vector vane at the 100 m level of the tower. Statistical equivalence in this context means that the frequency distributions of the classes are approximately equal at the same site and during the same period. The reliability of these schemes is investigated and compared to the standard scheme by correlation analysis. Finally, the schemes are compared with other commonly applied classification methods.