Observing the Equatorial, Post-Sunset F Region Ionosphere Using Direct Variational Sensitivity Analysis for HF Beacon Network Ray Tracing

Abstract:

Ionospheric plasma density irregularities are frequent features in the equatorial, post-sunset F region ionosphere that negatively affect radio communication. These irregularities exist on a wide variety of spatial scales and are intricately tied to local and regional ionospheric conditions. Incoherent and coherent scatter radar measurements allow scientists to investigate such density irregularities in localized study regions. A multistatic, HF radio beacon network surrounding the Jicamarca Radio Observatory aims to create a comprehensive picture of the regional ionosphere and contextualize irregularities observed by incoherent and coherent scatter radio modes. Through the use of this beacon network and direct variational sensitivity analysis for Hamiltonian ray tracing, we have observed the large-scale activity in the regional ionosphere, such as tilting and uplifting, that occurs before density depletions develop overhead. We utilize pseudorange and Doppler shift measurements to infer regional, volumetric electron number density. We will soon be integrating amplitude measurements as well as GPS total electron content measurements to gather information about D region absorption and parameterize the topside. In future work, we will assimilate beacon data into the Cornell Ionospheric Instability Simulation to work toward our overall goals: accurate space weather nowcasting and eventual space weather forecasting.