Ionospheric effects of the solar flares as deduced from global GPS network data

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 flares location on the Sun is investigated.

Estimating the contribution from different ionospheric regions to the TEC response to the solar flares using data from the international GPS network

“…By virtue of the fact that the response amplitude at high altitudes was found to be comparable with the level of background fluctuations, the method of coherent accumulation by Afraimovich (2000a) and Afraimovich et al (2000bAfraimovich et al ( , 2001a was used in an additional analysis. The essence of the method is that it involves a coherent summation of TEC responses to the solar flare, which are measured simultaneously with all LOS chosen for the analysis.…”

“…For flares lying closer to the disk center (CMD < 40 • ), an empirical dependence of the ionospheric TEC increase amplitude on the peak power of solar flares in the X-ray range was obtained (using data from the geostationary GOES-10 satellite). This paper is a logical continuation of the series of our publications (Afraimovich, 2000a;Afraimovich et al, 2000bAfraimovich et al, , 2001aAfraimovich et al, , b, c, 2002Leonovich et al, 2001) devoted to the study of ionospheric effects of solar flares, based on data from the international GPS network.…”

“…The TEC unit (TECU), which is equal to 10 16 el · m −2 and is commonly accepted in the literature, will be used throughout the text. Afraimovich (2000a) and Afraimovich et al (2000bAfraimovich et al ( , 2001a have developed a novel technology of a global detection of ionospheric effects from solar flares and presented data from first the GPS measurements of global response of the ionosphere to powerful impulsive flares of 29 July 1999 and 28 December 1999. The authors found that fluctuations of TEC are coherent for all stations on the dayside of the Earth.…”

“…No such effect on the nightside of the Earth has been detected yet. Afraimovich et al (2001cAfraimovich et al ( , 2002 and Leonovich et al (2001) have suggested a technique for estimating the ionospheric response to weak solar flares (of X-ray class C). They obtained a dependence of the ionospheric TEC increase amplitude (during the solar flare) on the flare location on the Sun (on the central meridian distance, CMD).…”

Summer‐winter hemispheric asymmetry of the sudden increase in ionospheric total electron content and of the O/N2 ratio: Solar activity dependence

“…Since the beginning of 21st century, the twodimensional imaging technique using TEC data from worldwide GPS receiver networks has been applied to SITEC studies [e.g., Afraimovich et al, 2001;Liu and Lin, 2004]. These studies have observed a solar zenith angle (SZA) dependence of SITEC [Zhang and Xiao, 2003;Wan et al, 2005].…”