The response of the ionosphere to faint and bright solar flares as deduced from global GPS network data

E L Afraimovich E L Afraimovich,L A Leonovich L A Leonovich,V V Grechnev V V Grechnev,A T Altynsev A T Altynsev

doi:10.4401/ag-3480

E L Afraimovich E L Afraimovich, L A Leonovich L A Leonovich + Show 2 more

Open Access

https://doi.org/10.4401/ag-3480

Copy DOI

Abstract

Results derived from analysing the ionosphere response to faint and bright solar flares are presented. The analysis used technology of a global detection of ionospheric effects from solar flares as developed by the authors, on the basis of phase measurements of the Total Electron Content (TEC) in the ionosphere using an international GPS network. The essence of the method is that use is made of appropriate filtering and a coherent processing of variations in the TEC which is determined from GPS data, simultaneously for the entire set of visible GPS satellites at all stations used in the analysis. This technique is useful for identifying the ionospheric response to faint solar flares (of X-ray class C) when the variation amplitude of the TEC response to separate line-on-sight to GPS satellite is comparable to the level of background fluctuations. The dependence of the TEC variation response amplitude on the bright flares location on the Sun is investigated.

Highlights

Introduction1971; Liu et al, 1996); Sudden Cosmic Noise Absorption (SCNA) (Deshpande and Mitra, 1972); Sudden Enhancement/decrease of atmospherics (SES) (Sao et al, 1970)
The enhancement of X-ray and ultraviolet (UV) emission observed during chromospheric flares on the Sun immediately causes an increase in electron density in the ionosphere
Sudden Ionospheric Disturbances (SID) are generally recorded as the Short Wave Fadeout (SWF) (Stonehocker, 1970); Sudden Phase Anomaly (SPA) (Jones, 1971; Ohshio, 1971); Sudden Frequency Deviation (SFD)

Summary

Introduction

1971; Liu et al, 1996); Sudden Cosmic Noise Absorption (SCNA) (Deshpande and Mitra, 1972); Sudden Enhancement/decrease of atmospherics (SES) (Sao et al, 1970). The effect of solar flares on the ionospheric F-region is manifested as a Sudden Increase of Total Electron Content (SITEC) which was measured previously using continuously operating VHF radio beacons on geostationary satellites (Mendillo et al, 1974b; Davies, 1980). The time profile of TEC responses is similar to the time behavior of hard X-ray emission variations during flares in the energy range 25-35 keV if the relaxation time of electron density disturbances in the ionosphere of order 50-100 s is introduced. No such effect on the nightside of the Earth has been detected yet. The objective of this paper is to use this technology for analysing the ionosphere response to faint and bright solar flares

Processing of the data from the GPS network

Ionospheric response to faint solar flare

Ionospheric response to bright solar flares

Discussion

Summary