Ionospheric <i>fo</i>F2 anomalies during some intense geomagnetic storms

Abstract

Abstract. The global evolutions of f oF2 anomalies were examined for three very intense geomagnetic storms, namely the Halloween events of October

Response of the Antarctic Ionosphere to Some Intense Geomagnetic Storms

“…The results observed during the main phase and the first part of the recovery are in agreement with previous observations [7,8,10,12].…”

“…Some studies performed with foF2 at high and subauroral latitudes in the Northern Hemisphere have found negative storm effects almost always during the main phase and recovery phase of geomagnetic storms [7,8].…”

Pre-storm <I>Nm</I>F2 enhancements at middle latitudes: delusion or reality?

“…In all cases considered either the NmF2 enhancements were related to moderate auroral activity or similar NmF2 enhancements took place during some previous days and such type of NmF2 variations have nothing to do with the following magnetic storms. Therefore, it is possible to conclude -there is no such an effect as the prestorm NmF2 enhancement as a phenomenon absolutely related to the following magnetic storm, to say nothing of using such enhancements as a precursor for the following magnetic storms (Kane, 2005;Blagoveschensky et al, 2006). It may seem that a moderate auroral activity characterized by AE=200-400 nT is not sufficient to produce the observed F2-layer positive effects, as many cases of NmF2 enhancements considered in the referred papers took place under such conditions, but this is a delusion.…”

“…Next step in this direction was undertaken by Kane (2005) who considered three periods with very large magnetic storms: 28-31 October 2003, 19-22 November 2003, and 13-14 March 1989. He found strong positive effects in foF2 within the 24 h period before the SC.…”

“…The problem of NmF2 pre-storm enhancements comes up from time to time in literature (Danilov et al, 1985;Danilov and Belik, 1992;Danilov, 2001;Kane, 2005;Buresova and Correspondence to: A. V. Mikhailov (avm71@orc.ru) Laštovička, 2007Liu et al, 2008;Blagoveschensky et al, 2006;Blagoveschensky and Kalishin, 2009). Both the morphology and plausible mechanisms are considered.…”