Effective electron recombination coefficient in ionospheric D-region during the relaxation regime after solar flare from February 18, 2011

TL;DR

This study models the time-dependent effective recombination coefficient in the ionospheric D-region during the relaxation phase after a solar flare, using VLF radio wave data to analyze ionospheric perturbations around 70 km altitude.

Contribution

We introduce a model for determining a weakly time-dependent recombination coefficient in the ionospheric D-region during flare relaxation, based on VLF signal analysis.

Findings

Recombination coefficient varies during the relaxation period.

VLF signal analysis reveals ionospheric response to solar flare.

Model accurately describes ionospheric perturbations post-flare.

Abstract

In this paper, we present a model for determination of a weakly time dependent effective recombination coefficient for the perturbed terrestrial ionospheric D-region plasma. We study consequences of a class M1.0 X-ray solar flare, recorded by GOES-15 satellite on February 18, 2011 between 14:00 UT and 14:15 UT, by analyzing the amplitude and phase real time variations of very low frequency (VLF) radio waves emitted by transmitter DHO (located in Germany) at frequency 23.4 kHz and recorded by the AWESOME receiver in Belgrade (Serbia). Our analysis is limited to ionospheric perturbations localized at altitudes around 70 km where the dominant electron gain and electron loss processes are the photo-ionization and recombination respectively.