Abstract. Six specialized radio receivers were developed to measure the Doppler shift of amplitude modulation (AM) broadcast radio carrier signals due to ionospheric effects. Five were deployed approximately in a circle at a one-hop distance from an 810 kHz clear-channel AM transmitter in Schenectady, New York, and the sixth was located close to the transmitter, providing a reference recording. Clear-channel AM signals from New York City and Connecticut were also received. The experiment confirmed detection of traveling ionospheric disturbances (TIDs) and measurement of their horizontal phase velocities through monitoring variations in the Doppler shift of reflected AM signals imparted by vertical motions of the ionosphere. Comparison of 12 events with simultaneous global navigation satellite system (GNSS)-based TID measurements showed generally good agreement between the two techniques slightly more than half the time and substantial differences slightly less than half the time, with differences attributable to differing sensitivities of the techniques to wave altitude and characteristics within a complex wave environment. Detected TIDs had mostly southward phase velocities, and in four cases they were associated with auroral disturbances that could plausibly be their sources. A purely automated software technique for event detection and phase velocity measurement was developed and applied to 1 year of data, revealing that AM Doppler sounding is much more effective when using transmitter signals in the upper part of the AM band (above 1 MHz) and demonstrating that the AM Doppler technique has promise to scale to large numbers of receivers covering continent-wide spatial scales.
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Crowdsourced Doppler measurements of time standard stations demonstrating ionospheric variability
Abstract. Ionospheric variability produces measurable effects in Doppler shift of HF (high-frequency, 3–30 MHz) skywave signals. These effects are straightforward to measure with low-cost equipment and are conducive to citizen science campaigns. The low-cost Personal Space Weather Station (PSWS) network is a modular network of community-maintained, open-source receivers, which measure Doppler shift in the precise carrier signals of time standard stations. The primary goal of this paper is to explain the types of measurements this instrument can make and some of its use cases, demonstrating its role as the building block for a large-scale ionospheric and HF propagation measurement network which complements existing professional networks. Here, data from the PSWS network are presented for a period of time spanning late 2019 to early 2022. Software tools for the visualization and analysis of this living dataset are also discussed and provided. These tools are robust to data interruptions and to the addition, removal or modification of stations, allowing both short- and long-term visualization at higher density and faster cadence than other methods. These data may be used to supplement observations made with other geospace instruments in event-based analyses, e.g., traveling ionospheric disturbances and solar flares, and to assess the accuracy of the bottomside estimates of ionospheric models by comparing the oblique paths obtained by ionospheric ray tracers with those obtained by these receivers. The data are archived at https://doi.org/10.5281/zenodo.6622111 (Collins, 2022).
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- PAR ID:
- 10474589
- Editor(s):
- David Carlson
- Publisher / Repository:
- Copernicus Publications
- Date Published:
- Journal Name:
- Earth System Science Data
- Volume:
- 15
- Issue:
- 3
- ISSN:
- 1866-3516
- Page Range / eLocation ID:
- 1403 to 1418
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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