EFFECTS OF GEOMAGNETIC-ACTIVITY ON THE F-REGION OF THE IONOSPHERE

A study is made of the effects of geomagnetic activity on F-region ionization by correlating the F-region parameters and the Kp and AE indices, using delays up to 33 h. The total electron content from a single station for the years 1971-74 as well as f{hook}0F2 from a longitudinal chain of stations around 150°E for the years 1968-74 were used. Initially the analyses were carried out using all the geomagnetic data. They were then divided according to high or low activity in order to separate magnetic storm from quiet magnetic effects. Data sets for each station consisted of 2-monthly segments for each hour of the day for each of the years. This enabled latitudinal, seasonal and sunspot cycle effects on the correlations to be detected. Significant positive correlations with delays greater than a few hours dominated the winter results at lower latitudes; the correlations being predominantly negative at higher latitudes. The summer results at all latitudes were dominated by negative correlations. Significant negative correlations with Kp at delays between 0-3 h were obtained for summer and autumn from higher latitude stations probably indicative of electric fields. The time lags greater than 3 h are consistent with changes in atmospheric neutral composition brought about by modification of the global thermospheric circulation following heating in the auroral zones. Analysis of hmF2 data for a mid latitude station showed a negative correlation of the peak height of the F-region with magnetic activity. © 1979.