Experimenting with frequency-and-angular sounding to characterize traveling ionospheric disturbances using the LWA-SV radio telescope and a DPS4D

Here we present near vertical angle of arrival and Doppler observations using a Digisonde Portable Sounder 4D (DPS4D) as a transmitter and the Long Wavelength Array at Sevilleta (LWA-SV) radio telescope as a receiver, over an 80-km baseline. With 256 dual-polarization dipole antennas, LWA-SV provides unparalleled sensitivity and angular resolution to high frequency sounding measurements of traveling ionospheric disturbances (TIDs). We conducted a study over 3 days in March 2018 and detected several TIDs ranging from 10- to 45-min periods. These medium scale TIDs were detected using an implementation of frequency-and-angular sounding (FAS), which was first described in Beley et al. (1995, https://doi.org/10.1029/95RS01992). FAS assumes an ionospheric mirror model and provides estimates of the wavelength, direction, and speed of TIDs using the measured angle of arrival and Doppler of a high frequency ionospheric reflection. We experiment with this method and show that LWA-SV is capable of achieving observations that are unmatched in sensitivity and resolution, allowing for measurements limited primarily by the errors accumulated by the assumptions within different manifestations of the FAS algorithm.