Exploring the effects of solar eclipses on radio wave propagation has been an active area of research since the first experiments conducted in 1912. In the first few decades of ionospheric physics, researchers started to explore the natural laboratory of the upper atmosphere. Solar eclipses offered a rare opportunity to undertake an active experiment. The results stimulated much scientific discussion. Early users of radio noticed that propagation was different during night and day. A solar eclipse provided the opportunity to study this day/night effect with much sharper boundaries than at sunrise and sunset, when gradual changes occur along with temperature changes in the atmosphere and variations in the sun angle. Plots of amplitude time series were hypothesized to indicate the recombination rates and reionization rates of the ionosphere during and after the eclipse, though not all time-amplitude plots showed the same curve shapes. A few studies used multiple receivers paired with one transmitter for one eclipse, with a 5:1 ratio as the upper bound. In these cases, the signal amplitude plots generated for data received from the five receive sites for one transmitter varied greatly in shape. Examination of very earliest results shows the difficulty in using a solar eclipse to study propagation; different researchers used different frequencies from different locations at different times. Solar eclipses have been used to study propagation at a range of radio frequencies. For example, the first study in 1912 used a receiver tuned to 5,500 meters, roughly 54.545 kHz. We now have data from solar eclipses at frequencies ranging from VLF through HF, from many different sites with many different eclipse effects. This data has greatly contributed to our understanding of the ionosphere. The solar eclipse over the United States on August 21, 2017 presents an opportunity to have many locations receiving from the same transmitters. Experiments will target VLF, LF, and HF using VLF/LF transmitters, NIST?s WWVB time station at 60 kHz, and hams using their HF frequency allocations. This effort involves Citizen Science, wideband software defined radios, and the use of the Reverse Beacon Network and WSPRnet to collect eclipse-related data.
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Receiver system design for crowdsourced experiments on the effects of a solar eclipse on low-frequency radio wave propagation
The goal of this project is to conduct the first geographically distributed, low-frequency skywave propagation measurements during a solar eclipse. There is a lack of knowledge about how radio waves below frequencies of 500 kHz are affected by a total eclipse and a lack of experimental data reflecting these low-frequency radio wave transmissions at geographically diverse locations during an eclipse. A low-frequency band receiver system for people across the United States to assemble and use is designed, allowing for a crowd-sourced collection of measurements of relative signal strength of the WWVB and Dixon low-frequency station signals during the eclipse over North America on August 21, 2017.
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- PAR ID:
- 10026339
- Date Published:
- Journal Name:
- 2016 IEEE International Symposium on Antennas and Propagation (APSURSI)
- Page Range / eLocation ID:
- 1261 to 1262
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Exploring the effects of solar eclipses on radio wave propagation has been an active area of research since the first experiments conducted in 1912. In the first few decades of ionospheric physics, researchers started to explore the natural laboratory of the upper atmosphere. Solar eclipses offered a rare opportunity to undertake an active experiment. The results stimulated much scientific discussion. Early users of radio noticed that propagation was different during night and day. A solar eclipse provided the opportunity to study this day/night effect with much sharper boundaries than at sunrise and sunset, when gradual changes occur along with temperature changes in the atmosphere and variations in the sun angle. Plots of amplitude time series were hypothesized to indicate the recombination rates and reionization rates of the ionosphere during and after the eclipse, though not all time-amplitude plots showed the same curve shapes. A few studies used multiple receivers paired with one transmitter for one eclipse, with a 5:1 ratio as the upper bound. In these cases, the signal amplitude plots generated for data received from the five receive sites for one transmitter varied greatly in shape. Examination of very earliest results shows the difficulty in using a solar eclipse to study propagation; different researchers used different frequencies from different locations at different times. Solar eclipses have been used to study propagation at a range of radio frequencies. For example, the first study in 1912 used a receiver tuned to 5,500 meters, roughly 54.545 kHz. We now have data from solar eclipses at frequencies ranging from VLF through HF, from many different sites with many different eclipse effects. This data has greatly contributed to our understanding of the ionosphere. The solar eclipse over the United States on August 21, 2017 presents an opportunity to have many locations receiving from the same transmitters. Experiments will target VLF, LF, and HF using VLF/LF transmitters, NIST’s WWVB time station at 60 kHz, and hams using their HF frequency allocations. This effort involves Citizen Science, wideband software defined radios, and the use of the Reverse Beacon Network and WSPRnet to collect eclipse-related data.more » « less
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Abstract In this study, we utilized both ground‐based and space‐borne observations including total electron content (TEC) from Beidou geostationary satellites, two‐dimensional TEC maps from the worldwide dense Global Navigation Satellite System receivers, ionosondes, and in situ electron density (
Ne ) and electron temperature (Te ) from both Swarm and China Seismo‐Electromagnetic Satellite satellites, to investigate the low‐latitude ionospheric responses to the annular solar eclipse on 21 June 2020. The decrease in TEC during the eclipse at low latitudes showed a local time dependence with the largest depletions in the noon and afternoon sectors. It was also found that the TEC depletions at different latitudes in the equatorial ionization anomaly (EIA) region over the East Asian sector cannot solely be explained by the solar flux changes associated with the obscuration rate. The differences in TEC reduction between stations can be more than a factor of 2 at latitudes with the same obscuration rate of over 90%. Compared with TEC variations in the Northern Hemisphere, the TEC also underwent a considerable decrease in the EIA region in the conjugate hemisphere without eclipse shadow. Meanwhile, theh m F 2near the magnetic equator increased around the onset of the eclipse, indicating an enhancement of the eastward equatorial electric field. Furthermore, the TEC decrease during the eclipse in the EIA region in both hemispheres lasted for a long period of more than 7 hr after the eclipse, with a TEC depletion of 2–6 TEC units. TheNe from Swarm and China Seismo‐Electromagnetic Satellite satellites showed a complicated variation after the eclipse, whereas no visible change was observed inTe . The enhanced equatorial electric field, neutral wind changes, and the associated plasma transport act together to generate the observed ionospheric effects at low latitudes during the eclipse. Our results also suggest that the eclipse‐induced perturbations of dynamic processes can continue to impact the ionosphere after the eclipse. -
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/APS.2016.7696338
