Ionospheric D-region response to the 22-26 March 2023 Intense Geomagnetic Storm: a manifestation on Very Low Frequency (VLF) Radio Wave Signals received in the Eastern Mediterranean 

Abstract

The idea of searching for the manifestations of solar and geomagnetic events on a very low frequency and low frequency (VLF/LF, 3-30/0.5-470 kHz) radio signals as a means of probing the ionospheric  D-region has drawn much attention in the last few decades. In this study, we present the impacts of the 22-26 March 2023 geomagnetic storm (GS) observed from the Atmospheric Weather Electromagnetic System for Observation Modeling and Education (AWESOME) VLF/LF radio waves receiver located in Ariel University, Israel.  The station collects narrowband (NB) and broadband (BB) data of electromagnetic waves originating from various global VLF transmitters, and also from natural sources such as lightning discharges around the globe to complement other available data sources from ground- and space- based observatories. Our careful analysis of the received LF signals amplitude and phase, under distinct GS phases (initial, main and recovery stages), revealed significant spatial and temporal variations along the different transmitters’ propagation path, both for the N/S and the E/W signal channels.  Such manifestations include both signal enhancement (up to several dB) and signal attenuation. Additionally, analysis between other available data sources from ground- and space- based observatories, such as high (SYM-H) and low (Dst) time resolution GS indices under the three GS regimes, was conducted via a wide range of correlation techniques.