The time-weighted magnetic indices ap(tau), PC(tau), AE(tau) and their correlation to the southern high latitude ionosphere

In this investigation different data transformations of the ionospheric cha racteristic foF2 from high latitude stations in the Southern Hemisphere are considered and correlated with time weighted accumulation of the geomagnet ic indices ap, AE and PC. The analysis, performed during periods of severe magnetic activity, shows a decrease in foF2 as a consequence of geomagnetic perturbations and a characteristic response recovery time t ranged between 15-20 hours. The best correlation coefficients are obtained by comparing t he time weighted accumulation of the auroral index AE and a data transforma tion based on the ratio NmF2(t)/NmF2(M) where NmF2(t) is the hourly maximum electron density at the F2 peak layer and NmF2(M) is its monthly median va lue. (C) 2001 Elsevier Science Ltd. All rights reserved.