Waves of ionization are rippling through Earth's upper atmosphere in response to the recent onslaught of solar flares. This affects the propagation of radio signals--suppressing some frequencies and boosting others. By monitoring distant transmitters at a frequency of 23.4 kHz, of Bojnice, Slovakia detected nearly a dozen sudden ionospheric disturbances (SIDs) on Feb. 18th:

Ionization Chart
© Rudolf SlosiarHere is a chart from an observatory in Bojnice, one of the upcoming SID monitor the network. Individual peaks match exactly with the events as recorded by satellite SDO. It turns out that the greater the ionospheric D layer exposed to more radiation, the results of this method are more persuasive. Image taken: Feb. 18, 2011. Location: Bojnice, Slovakia
"Each surge in signal strength corresponds to a specific solar flare," notes Slosiar. "Individual peaks exactly match events recorded by Earth-orbiting satellites."

More waves of ionization are iin the offing as sunspot complex 1161-1162 continues to crackle with M-class solar flares. The next SID could be over your backyard. Do-it-yourself SID monitors are available from Stanford University.

More SIDS:
From Roberto Battaiola of Pantigliate, Milan, ITALY; from Jan Karlovsky of Hlohovec, Slovakia; from Rob Stammes of Laukvik, Norway.