Deep Electron Density Depletion Near Sunset Terminator on St. Patrick's Day Storm and Its Impacts on Skywave Propagation

Abstract

During the active space weather periods, the transfer of solar wind energy and momentum to Earth's magnetosphere-ionosphere system leads to a variety of neutral and electrodynamical processes causing severe disturbances in the ionosphere. The equatorial Ionosphere is one of the most vulnerable regions that exhibit dramatic changes in electron density distribution during this period. During geomagnetic storms, the particle and joule heating at high latitudes drives a global scale thermospheric wind dynamo, generally known as Ionospheric Disturbance Dynamo (IDD) (Blanc & Richmond, 1980). Further, the high latitude region 1 and region 2 field-aligned currents also induce strong convection and overshielding electric fields which penetrates promptly to the equatorial ionosphere, known as Prompt Penetration Electric Field (PPEF) (Kikuchi et al., 1996(Kikuchi et al., , 2000Nishida, 1968). The electric field perturbation associated with the above processes (IDD, strong convection, and overshielding electric fields) as well as neutral disturbances can significantly alter the electron density distribution of equatorial and low latitude ionosphere (

Iterative Gradient Correction (IGC) Method for True Height Analysis of Ionograms

“…Therefore, the results presented in Figure 1 and those in Figure 1 of Ankita et al. (2023) successfully demonstrate the accuracy of the HFPS.…”

“…They have used the true height profile given by ARTIST to simulate the Ionosonde experiment, and the virtual heights are derived for both ordinary and extraordinary modes of propagation. The derived virtual height curves were found to match accurately with the ionogram traces (Figure 1 of Ankita et al, 2023). Therefore, the results presented in Figure 1 and those in Figure 1 of Ankita et al (2023) successfully demonstrate the accuracy of the HFPS.…”

“…The derived virtual height curves were found to match accurately with the ionogram traces (Figure 1 of Ankita et al, 2023). Therefore, the results presented in Figure 1 and those in Figure 1 of Ankita et al (2023) successfully demonstrate the accuracy of the HFPS.…”

“…Ankita et al. (2023) have also validated the accuracy of this HFPS using the Digisonde observations at Millstone Hill. They have used the true height profile given by ARTIST to simulate the Ionosonde experiment, and the virtual heights are derived for both ordinary and extraordinary modes of propagation.…”

“…In this method, we use an in-house developed HF Propagation Simulator (HFPS) that computes the propagation path of radio waves under the given ionospheric electron density distribution (Ankita et al, 2023). This HFPS solves the ray equations given by Haselgrove (1954Haselgrove ( , 1963, which incorporate geometric optics and the ray paths through plasma.…”