Sensing the Earth's low ionosphere during solar flares using VLF signals and GOES X-ray data

TL;DR

This study investigates how solar X-ray flares influence the Earth's low ionosphere by analyzing VLF signal perturbations and GOES X-ray data, revealing that different flares cause distinct changes in ionospheric electron density profiles.

Contribution

It presents a novel analysis of ionospheric variations during solar flares using VLF signals and GOES data, applying LWPC modeling to estimate waveguide parameters.

Findings

Solar flares alter VLF signal amplitude and phase delay.

Different flares produce distinct ionospheric electron density changes.

The study enhances understanding of ionospheric response to solar activity.

Abstract

An analysis of D-region electron density height profile variations, induced by four isolated solar X-ray flares during period from September 2005 to December 2006, based on the amplitude and the phase delay perturbation of 22.1 kHz signal trace from Skelton (54.72 N, 2.88 W) to Belgrade (44.85 N, 20.38 E), coded GQD, was carried out. Solar flare data were taken from NOAA GOES12 satellite one-minute listings. For VLF data acquisition and recordings at the Institute of Physics, Belgrade, Serbia, the AbsPAL system was used. Starting from LWPCv21 code (Ferguson, 1998), the variations of the Earth-ionosphere waveguide characteristic parameters, sharpness and reflection height, were estimated during the flare conditions. It was found that solar flare events affected the VLF wave propagation in the Earth-ionosphere waveguide by changing the lower ionosphere electron density height profile, in a different way, for different solar flare events.