Influence of solar extreme ultraviolet radiations on artificial very-low-frequency waves in near-earth space

TL;DR

This paper explores how solar extreme ultraviolet radiation affects artificial VLF waves in near-Earth space, revealing significant attenuation in certain regions.

Contribution

The study identifies the influence of solar EUV radiations on artificial VLF wave propagation in the inner radiation belt and slot region.

Findings

Enhanced solar EUV radiations cause global attenuation of artificial VLF waves from low-latitude transmitters.

Artificial VLF waves from middle-latitude transmitters weaken slightly around noon under high solar EUV radiations.

Collisional damping of ionospheric plasmas at low latitudes causes large attenuation of VLF waves in low L regions.

Abstract

Ground-based very low frequency (VLF) transmitter waves (3 – 30 kHz) can cause the precipitation loss of high-energy electrons in Earth’s radiation belts. Although the propagation and attenuation of artificial VLF waves have been studied for more than half a century, it is not clear whether solar extreme ultraviolet (EUV) radiations can modify the VLF wave intensity in inner radiation belt and slot region (L ~ 1.1 – 3RE). Here, by analyzing satellite observations and quantitative calculations, we find that the enhanced solar EUV radiations cause global attenuation of the artificial VLF waves radiated from low-latitude transmitters (λ < 44.2° or L < 1.8 RE), whereas those waves radiated from middle-latitude transmitters (λ > 44.2° or L > 1.8 RE) weaken slightly around noon. Under high solar EUV radiations, the large attenuation of artificial VLF waves in the low L region is due to enhanced collisional damping of ionospheric plasmas at low latitudes.

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