Exploiting LF/MF signals of opportunity for lower ionospheric remote sensing

• Published in: Geophysical research letters Vol. 44; no. 16; pp. 8665 - 8671
• Main Authors: Higginson‐Rollins, Marc A., Cohen, Morris B.
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 28.08.2017
• Subjects: 300 kHz; Communication; D region; Data processing; Detection; Diagnostic software; Diagnostic systems; Frequencies; Geophysics; groundwave modeling; High frequencies; High frequency; Ionosphere; Ionospheric disturbances; Ionospheric propagation; low frequency (LF); lower ionosphere; medium frequency (MF); Methods; Modelling; Radio; Receivers & amplifiers; Reflectance; Remote sensing; Temporal resolution; Terrestrial environments; Transmitters; Very high frequencies; Very Low Frequencies
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/2017GL074236

We introduce a method to diagnose and track the D region ionosphere (60–100 km). This region is important for long‐distance terrestrial communication and is impacted by a variety of geophysical phenomena, but it is traditionally very difficult to detect. Modern remote sensing methods used to study the D region are predominately near the very low frequency (VLF, 3–30 kHz) band, with some work also done in the high‐frequency and very high frequency bands (HF/VHF, 3–300 MHz). However, the frequency band between VLF and HF has been largely ignored as a diagnostic tool for the ionosphere. In this paper, we evaluate the use of 300 kHz radio reflections as a diagnostic tool for characterizing the D region of the ionosphere. We present radio receiver data, analyze diurnal trends in the signal from these transmitters, and identify ionospheric disturbances impacting LF/MF propagation. We find that 300 kHz remote sensing may allow a unique method for D region diagnostics compared to both the VLF and HF/VHF frequency bands, due to a more direct ionospheric reflection coefficient calculation method with high temporal resolution without the use of forward modeling. Key Points The frequency band around 300 kHz has been largely ignored for the purposes of ionospheric remote sensing Utilizing these beacons may provide the temporal and spatial capabilities that both VLF and HF remote sensing cannot achieve A new highly sensitive receiver can detect 300 kHz signals as far as 2500 km away, potentially opening up continental‐scale measurements