High-Frequency Beacon Network Analysis in Alaska: Ionospheric Specification and Doppler and Range Spread Characterization

A high-frequency (HF) beacon network has been deployed in Alaska. This network utilizes continuous wave HF signals that employ unquantized random phase codes with pseudorandom noise (PRN) encoding. The observables include group delay, Doppler shift and amplitude. These observables were derived by clustering spectral data collected every minute and applying Gaussian fitting techniques. The parameters obtained from this fitting also help describe the Doppler and range spread for each spectrum.

The HF beacons, along with other instruments such as GPS, are used to reconstruct the ionospheric electron number density regionally. A forward model based on geometric optics in an inhomogeneous, anisotropic, lossy plasma has been employed for this purpose. To model the ray amplitudes and solve the two-point boundary problem for each ray, a sensitivity analysis is necessary. We conduct the sensitivity analysis using reverse-mode automatic differentiation.

In this study, we present and analyze the regional electron density estimations based on data collected on November 8, 2023, during the evening hours in latitudes corresponding to the main trough, which is a large-scale nighttime depletion region. Additionally, we analyze how our estimations compare with the Poker Flat ISR measurements and sounder data. We also compare our Doppler and range measurements against previously established HF models used for characterization.