Evidence for Near-Equatorial Deposition by Energetic Electrons in the Ionospheric F-layer

Abstract

Near-equatorial great enhancements of the quasi-trapped >30 keV electrons at low-altitudes are studied during strong geomagnetic storms. We have found that the transient phenomenon often began at the morning and was capable to live several hours predominantly over the Pacific region with flux intensities largely exceeded quiet-time level by 4-5 orders of magnitudes. The purpose of the study is to validate an assumption that the enhanced quasi-trapped electron fluxes can be an important source of the ionization in the topside ionosphere in the range between the low and middle latitudes and to estimate energy deposition. We show that ionizing particle effect can significantly contribute in storm-time increase of total electron content (TEC) or positive ionospheric storm. We present analysis of medium/great flux events during moderate/major storms on 22 July 2009 and 27 July 2004 as examples for demonstrating concomitances of enhanced electron fluxes with ionospheric storm positive phases. Addition experimental support concerning the F2-region rise was obtained from COSMIC/FS3 radio occultation data for the storm of 22 July 2009.