Modeling and Validating a SuperDARN Radar's Poynting Flux Profile

Abstract

We have developed a model that simulates the Poynting flux profile of the Saskatoon Super Dual Auroral Radar Network (SuperDARN) radar at ionospheric altitudes. The model uses ray tracing software to project the radar system's vacuum Poynting flux profile through the ionosphere, taking into account the influence of the ionospheric medium on the propagation characteristics of the high frequency radio waves. Measurements of the radar's transmissions by the Radio Receiver Instrument (RRI) in low‐Earth orbit are used to validate the model during five experiments which occurred between 4 and 8 August 2017. Comparisons between simulated and measured RRI antenna voltages show good agreement, although there are clear instances in which the model underperforms. Nevertheless, the model demonstrates its utility as a tool for interpreting RRI measurements of SuperDARN radars. The model also helps address a lack of knowledge of a SuperDARN radar's Poynting flux profile at ionospheric altitudes. In particular, we assess the assumption that SuperDARN's scattering volume lies along the great‐circle path of the transmitting beam's bearing. Comparisons between the model and RRI's measurements show that this assumption is reasonable for the five experiments investigated in this work. The model presents a new way of carrying out SuperDARN and high frequency radio science investigations.

On the use of SuperDARN Ground Backscatter Measurements for Ionospheric Propagation Model Validation

“…Unfortunately, array gain pattern data is not commonly available for the TTFD type antennas due to the novelty of their design, and so in this study we make use of the LPDA array gain data from Perry et al [8]. The primary difference between the TTFD and LPDA arrays besides the exact gain pattern is a slightly reduced maximum gain, and an increased beamwidth and front to back ratio.…”

“…These GB measurements have found increasing utility over time, showing use for interferometer calibration [4] and real time determination of ionospheric parameters including fof2 [5] and maximum useable frequency (MUF) [6]. Climatological studies using GB data have also been performed by [7] and [8] to determine occurrence rates, with [7] additionally assessing the impact of the underlying ground scattering surface.…”

On the use of SuperDARN Ground Backscatter Measurements for Ionospheric Propagation Model Validation

“…NRT is a technique widely employed to study HF propagation through the ionosphere and is well suited for simulating SuperDARN backscatter. NRT has been previously used by Perry et al (2022) for example in the context of SuperDARN to validate the Saskatoon radar's gain pattern. This study makes use of the HFRM (high-frequency raytracing model) 2D NRT toolbox developed by the University of Birmingham's Space Environment and Radio Engineering (SERENE) group and is used to model the expected signal paths for the Blackstone radar beam 16 with the IRI-2016 ionospheric model.…”

“…Whilst gain pattern data for the TTFD antenna elements have been modelled by Custovic et al (2011) and for the array by Sterne et al (2011), numerical data was not provided. Data for beam 7 of the Saskatoon radar was provided by Perry et al (2022); however, no other beams are provided.…”

“…NEC is a software program for the modelling of thin wire antennas developed at the Lawrence Livermore National Laboratory by Burke and Poggio (1981). This program was selected due to its prior use by Custovic et al (2011), Sterne et al (2011 and Perry et al (2022). Far field radiation patterns are generated at 1 MHz intervals for beam 16 of the TTFD array, respectively.…”