Articles | Volume 13, issue 5
Ann. Geophys., 13, 532–540, 1995
https://doi.org/10.1007/s00585-995-0532-y
Ann. Geophys., 13, 532–540, 1995
https://doi.org/10.1007/s00585-995-0532-y

  31 May 1995

31 May 1995

Daytime F2-layer positive storm effect at middle and lower latitudes

A. V. Mikhailov, M. G. Skoblin, and M. Förster A. V. Mikhailov et al.

Abstract. Daytime F2-layer positive storm effects at middle and lower latitudes in the winter thermosphere are analyzed using AE-C, ESRO-4 neutral gas composition data, ground-based ionosonde observations and model calculations. Different longitudinal sectors marked by the storm onset as 'night-time' and 'daytime' demonstrate different F2-layer positive storm mechanisms. Neutral composition changes in the 'night-time' sector with increased [O] and [N2] absolute concentrations, while (N2/O)storm/(N2/O)quiet\approx1 at F2-layer heights, are shown to contribute largely to the background NmF2 increase at lower latitudes lasting during daytime hours. Storm-induced surges of the equatorward wind give rise to an additional NmF2 increase above this background level. The mid-latitude F2-layer positive storm effect in the 'daytime' sector is due to the vertical plasma drift increase, resulting from the interaction of background (poleward) and storm-induced (equatorward) thermospheric winds, but not to changes of [O] and [N2] concentrations.