VLF transmitters as tools for monitoring the plasmasphere

TL;DR

This paper demonstrates how VLF transmitters and satellite measurements can be used to accurately determine plasmaspheric electron densities, offering a new tool for plasma monitoring.

Contribution

It introduces a novel inversion method using VLF wave characteristics to derive plasmaspheric electron densities, validated against in-situ measurements.

Findings

Good agreement between inverted and in-situ densities

Method can provide densities where no direct measurements exist

Supports use of VLF signals for plasmaspheric monitoring

Abstract

Continuous burst mode VLF measurements were recorded on the RBSP/Van Allen Probes satellites and are analyzed to detect pulses from the Russian Alpha (RSDN-20) ground-based navigational system. Based on the wave characteristics of these pulses and on the position of the spacecraft, the signals propagated mostly in ducted mode in the plasmasphere. Knowledge of the propagation path allowed us to carry out a monochromatic wave propagation inversion to obtain plasmaspheric electron densities. We compared the obtained densities with independent in-situ measurements on the spacecraft. The results show good agreement, validating our inversion process. This contributes to validating the field-aligned density profile model routinely used in the inversion of whistlers detected on the ground. Furthermore, our method can provide electron densities at regimes where no alternative measurements are available on the spacecraft. This raises the possibility of using this method as an additional tool to measure and monitor plasmaspheric electron densities.