When Day Becomes Night, a Ham Radio Researcher Probes the Atmosphere
Standing on a back porch in Gilbertsville, Kentucky, nearly 1,000 miles from Newark, Nathaniel Frissell, ham radio in hand, took in the staggering spectacle unfolding overhead on Monday as the Earth was shrouded in eerie, midday twilight.
“It began with a small bite out of the Sun, and then the day got progressively darker and cooler, like the onset of a thunderstorm. By the time totality started, it had become almost twilight,” he recounted. “We took off our glasses and stared at the Sun, which appeared as a black disk, ringed with bright, flame-shaped light. We were looking at the corona with the naked eye.”
Stationed directly along the eclipse’s “path of totality,” Frissell, an assistant research professor of physics at NJIT’s Center for Solar-Terrestrial Research, was not just there to observe, however, but to lead one of the largest ionospheric experiments in the history of space science.
He spent the day making contact via a 102-ft. wire antenna with a network of ham radio operators he’d assembled around the world to test the strength and reach of their high frequency signals as one measure of the eclipse’s impact on Earth’s atmosphere. By early that morning, more than 1,300 operators had registered to take part in his Solar Eclipse QSO Party as “citizen-scientists” by recording their contacts with one another during the event.
Ham radio operators are able to communicate with each other across thousands of miles, despite the Earth’s curvature, by using high-frequency radio waves that bounce off the ionosphere – the electrified region of Earth’s upper atmosphere formed when ultraviolet light from the Sun dislodges electrons from neutral particles such as oxygen, nitrogen, and helium – and are refracted back down on the other side of the globe. The composition of the ionosphere at different levels affects their ability to transmit.
By blocking the Sun’s radiation, the shadow of the eclipse should have caused a decrease in ionospheric electron density, strongest in the region of totality, Frissell surmised. Within that region, conditions would be most similar to night, therefore enhancing the strength and reach of lower band signals, while degrading the propagation of higher bands.
He explained: “Low frequencies are more susceptible to ionospheric absorption than higher frequencies. They are therefore enhanced when ionospheric densities, and hence absorption, are reduced. Higher frequencies, on the other hand, require a denser ionosphere for signals to be refracted back to Earth. The decreased ionospheric densities caused by the eclipse shadow should have caused more high band signals will escape into space.
“The day started off with a lot of activity, but there seemed to be a drop-off as we got closer to the eclipse,” he added, cautioning, however, “This is all very anecdotal at this point. We have just begun to compile data from the day recorded by our network, as well as three others. I’m organizing it into six bands of radio frequency, from 1.8 to 28 MHz, and I will measure how these different wavelengths behaved at various times following the path of totality.”
Frissell, a sophisticated practitioner of ham radio who is intent on elevating the technology’s role in space science research, has been preparing for this rare event for more than two years. While a Ph.D. student at Virginia Tech, he founded the Ham Radio Science Citizen Investigation (HamSCI), an organization that connects professional researchers such as space physicists and astronomers with the amateur radio community. By merging their data, the different groups will be able to construct a comprehensive picture of atmospheric effects caused by space weather events ranging from the solar eclipse later this month to more common phenomena, such as solar flares. In 2014, he first demonstrated the use of ham radio data by showing the effects of an X-class solar flare on high frequency communications.
He will share his data and analysis from the eclipse at the American Geophysical Union annual meeting in December.
Two days before the eclipse, Joshua Katz '19, a computer science major and member of the NJIT K2MFF Amateur Radio Club who is working with Frissell, and Shaheda Shaik, a graduate student researcher at NJIT’s Center for Solar-Terrestrial Research, gave a night-time talk on the eclipse to a packed house at the United Astronomy Clubs of New Jersey (UACNJ) observatory at Jenny Jump State Forest. On Monday, Katz and other members of the club, including Joshua Vega '19, a computer science major (below with Kenneth Brown '71, president of the ham radio club his senior year) returned to the observatory NJIT K2MFF Amateur Radio Club to participate in the HamSCI Eclipse Ham Radio experiments.