Determining cross-wind variance for low frequency wind Meander

Long-period wind measurements carried out at 21 m by the Met. Research Unit, Cardington, England, have been processed to obtain estimates of low-frequency cross-wind variance, for application in Lagrangian models of atmospheric dispersion. Autocorrelation functions and power spectra were computed from long series (typically about 4000) 10 min mean winds, and the results used to obtain eddy variance and some information on characteristic timescales for frequencies occupying the ‘gap’ between resolved motions and high-frequency turbulence - i.e. the horizontal meander. It was felt that the results of the analysis merited wider dissemination in view of the importance of estimates of low-frequency cross-wind variance to the dispersion modelling community.