Both professional and citizen scientists conducted formal and informal investigations into the effect of the August 21 solar eclipse on HF radio propagation. Nathaniel Frissell, W2NAF, of HamSCI, has said it will take some time to get a more scientific analysis of data compiled during the Solar Eclipse QSO Party. Frissell and others are investigating whether the sudden absence of sunlight during the eclipse — and especially of solar ultra-violet and x-rays — would briefly change the properties of the upper atmosphere. Professional ionospheric researcher Phil Erickson, W1PJE, of the Atmospheric Sciences Group at MIT’s Haystack Observatory, said he can say categorically that there was a definite, large, and measurable effect in the ionosphere from the eclipse.
“We saw a 2X reduction in electron density during the eclipse for at least 45 minutes to 1 hour,” Erickson told ARRL. “This reduction had direct impacts on HF propagation along the bottom side.” Erickson said many models and observations exist from previous eclipses that demonstrate these effects. Erickson said MIT researchers used a “megawatt-class Thomson scatter radar” which can directly measure the plasma state of the ionosphere, including electron density, across a huge area in the eastern US.
“Scientists in the worldwide space physics community will be using these and many other eclipse observations to learn more about our ionosphere, space weather, and its effects on navigation and communication signals including amateur radio,” Erickson said. He has shared his data with the HamSCI team.