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

In this investigation different data transformations of the ionospheric characteristic foF2 from high latitude stations in the Southern Hemisphere are considered and correlated with time weighted accumulation of the geomagnetic 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 the time weighted accumulation of the auroral index AE and a data transformation 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 value.