Storm-time increases in the ionospheric total electron content

Abstract

CHANGES in the total electron content of the mid-latitude ionosphere during the first day of each of 20 geomagnetic storms have been monitored by Papagiannis et al.¹. They have shown that during the positive phase of the storms the magnitude of the increase in total electron content exhibits a very pronounced maximum near sunset. Although Rishbeth and Hanson² have shown that plasma convergence in the F region itself cannot account for the observed increases, an inward meridional E×B drift of the plasma may compress the H⁺ gas at great heights^1,2, giving rise to a field-aligned flow of H⁺ into the ionosphere. We have investigated the consequences of fieldaligned H⁺ flow by integrating the F region–protonosphere equations of motion and continuity for O⁺ and H⁺ along magnetic tubes that are undergoing E×B drift. The range of integration is from the lower F region to the equatorial crossing point of the magnetic tube, the method of integration being essentially that of Moffett and Murphy³. Our results support the idea that an influx of ionisation from the protonosphere may be partly responsible for some storm-time increases in ionosphere content.