LASP Magnetosphere Seminars

Abstract

The ionosphere serves as a natural filter for different energy EPP as higher energy particles penetrate deeper. Looking at the D-region (60-90 km) filters out all but the highest energy precipitating particles (>30 keV). The D-region ionosphere however is challenging to measure due to its combination of altitude and relatively low plasma density. A common way to continuously probe the D-region is to monitor Very Low Frequency (VLF) signals that reflect off the D-region plasma and propagate efficiently over thousands of kilometers. By assimilating multiple measurements from VLF signal paths that overlap, we are able to spatially resolve enhancements/depletions to D-region electron density. The Array for VLF Imaging of the D-region was designed for this exact case and came online in 2024. This presentation describes AVID, overviews the measurement and assimilation technique, and presents early data from a geomagnetic storm showing the likely capture of particle precipitation patches in the D-region.