There's a nice article at https://www.spaceweather.com/ about how
reception of WWV at remote locations was affected by the eclipse,
specifically Doppler shifts as the reflective layers of the ionosphere
moved up and down as the sun's energy was suddenly removed. The work
cited in the article was part of the HamSci (https://hamsci.org) project
that I've been part of.
We WWV (and CHU) see Doppler shifts of up to a couple of Hz every
morning and evening so that in itself isn't unusual. What was unique is
the opportunity to observe the shift from day to night propagation and
back over a few minutes.
Another part of the Case experiment, not mentioned in the article, is
taking advantage of an even more unique opportunity -- standard time and
frequency station CHU in Ontario, Canada, was very near the totality
path The Case group recruited a number of WebSDR receiver sites that
experienced totality to monitor the three CHU frequencies (3330, 7850,
and 14670 kHz) for effects on paths following the eclipse line. In
addition to frequency changes, they are looking for changes in the time
of arrival of the seconds ticks. The set of KiwiSDR receivers that I
run in central Ohio contributed data to that project.
A lot of other propagation-related experiments were running as well. My
station also saved the entire AM broadcast band as IQ data on disk
(about 1.1TB total), and we are watching multiple station carriers on
each channel pop in and out of view around the eclipse peak. There were
strong signal strength changes as well as Doppler shifts.
Lots of neat science will come out of all this.
John