DISPERSION IN IONOSPHERIC DRIFTS OVER PATIALA

The cross-spectral analysis has been applied to ionospheric drift reco rds obtained at Patiala during the years 1987-88 and 1989-90. Positive dispersion is predominant in the E region and random dispersion in th e F region. About 10% of the records show no dispersion and only in th ese cases the drift motion can be described by single velocity paramet er given by similar fade and full correlation analysis. Negative dispe rsion is observed only in 4% of cases in the E region and 5% of cases in the F region. Characteristic velocity is high in case of random or large positive dispersion. The positive dispersion is probably due to two or more scale size structures moving with different speeds in the same direction, while random dispersion is due to several scale size s tructures moving with different speeds and in different directions.