The Effect of the 21 August 2017 Total Solar Eclipse on the Phase of VLF/LF Signals

Abstract

An experimental study of the phase and amplitude observations of sub‐ionospheric very low and low frequency (VLF/LF) signals is performed to analyze the response of the lower ionosphere during the 21 August 2017 total solar eclipse in the United States of America. Three different sub‐ionospheric wave paths are investigated. The length of the paths varies from 2,200 to 6,400 km, and the signal frequencies are 21.4, 25.2, and 40.75 kHz. The two paths cross the region of the total eclipse, and the third path is in the region of 40–60% of obscuration. None of the signals reveal any noticeable amplitude changes during the eclipse, while negative phase anomalies (from −33° to −95°) are detected for all three paths. It is shown that the effective reflection height of the ionosphere in low and middle latitudes is increased by about 3–5 km during the eclipse. Estimation of the electron density change in the lower ionosphere caused by the eclipse, using linear recombination law, shows that the average decrease is by 2.1 to 4.5 times.

Some Features of the Ionospheric Radio Wave Characteristics Over China Observed During the Solar Eclipse of 21 June 2020

“…The effects that solar eclipses have on radio wave characteristics have been studied to a significantly lesser degree. These issues have been addressed by Kascheev et al (2009), Garmash et al (2011), Chen et al (2015), Uryadov et al (2016), Cohen et al (2018), and Rozhnoi et al (2020).…”

Impact of Three Solar Eclipses of 2019–2020 on the D‐Region Ionosphere Observed From a Subtropical Low‐Latitude VLF Radio Station

“…Observations of VLF/LF signals modification during a solar eclipse were first documented by Bracewell (1952). Since then there are numerous studies of VLF/LF signal perturbations during solar eclipses (Chakrabarti et al., 2010, 2012; Clilverd et al., 2001; Guha et al., 2010; Inui & Hobara, 2014; Lynn, 1981; Rozhnoi et al., 2020; Sengupta et al., 1980). Modification of the D‐region conductivity profile changes the reflection heights of the VLF signals during a solar eclipse producing detectable phase and amplitude anomalies (De et al., 2011).…”