Observations and Modeling of Traveling Ionospheric Disturbance Signatures From an Australian Network of Oblique Angle-of-Arrival Sounders

Abstract

A network of oblique angle-of-arrival (AoA) ionosondes was installed as part of the Elevation-scanned Oblique Incidence Sounder Experiment (ELOISE) in September 2015. The ELOISE experimental campaign was designed to study the spatial and temporal structure of ionospheric variability at midlatitudes, of which traveling ionospheric disturbances are a key component. The new AoA sounder makes use of Defence Science and Technology Group's direct-digital high-frequency transmitter and receiver technology, to enable multichannel collection of both ionograms and channel scattering functions (Doppler spectra) on a common 2-D array. In this paper, the array design and onboard signal processing for the AoA sounder is described, along with a sample of results showing typical disturbance signatures across the delay, Doppler frequency, bearing, and elevation measurements. Realistic parameterized models of electron density perturbations, along with geometric ray tracing, were used to synthesize the effects of medium- to large-scale traveling ionospheric disturbances on the sounder observables and aid in interpreting the measured signatures.