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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On the use of solar eclipses to study the ionosphere
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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- Award ID(s):
- 1638685
- NSF-PAR ID:
- 10026297
- Date Published:
- Journal Name:
- 15th International Ionospheric Effects Symposium
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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The very first use of the solar eclipse to study the ionosphere was done in 1912 at a wavelength of 5,500 meters. Since that time, multiple studies have been done at VLF and LF frequencies. Most of these studies were performed at a single receive site with a single transmit location during a single eclipse, thus making it very hard to compare data from separate collections. This paper addresses historical collection efforts, what has been learned about the sun’s influence upon the ionosphere, and the role of neutral corpuscular particles ionizing the ionosphere. Questions raised by the above will be addressed. A planned crowdsource effort will then be described that will attempt to address and answer questions raised by having multiple receivers all reporting on signals transmitted by the same VLF/LF stations. There are two approaches to the crowdsource collection. One approach uses the SuperSID network that is already reporting on changes in propagation of signals from VLF stations. The other approach uses a receiver and antenna based upon an instrumentation amplifier chip and a smart phone as a software defined radio. The later approach will be detailed.more » « less
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Accepted Manuscript1.0
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