for Thursday

GEOMAGNETIC STORM WATCH: NOAA forecasters say there is a chance of minor G1-class geomagnetic storms late on June 23rd when a CME might hit Earth’s magnetic field. This is the same CME hurled into space by an X1-class solar flare on June 20th. At first it appeared the CME would miss Earth; however, additional modeling suggests a glancing blow might be possible. Solar flare alerts: SMS Text

A NEW WAY TO DETECT SOLAR FLARES: Around the world, ham radio operators are experimenting with a new way to detect solar flares–the Doppler Shift method. Brian Curtis of Sault Ste Marie, Michigan, demonstrated the technique during the June 20th X-flare:

“I monitor the frequency and field strength of Canada’s CHU time station transmitting at 7850 KHz,” explains Curtis. “During the X-class flare event, I was able to detect the Doppler shift of the station’s carrier frequency (green plot). It shifted by 5 Hz, which is a small change, but very obvious!”

When radiation from a solar flare hits Earth’s atmosphere, it ionizes the air, temporarily boosting the thickness of our planet’s ionosphere. Any radio station skipping off the ionosphere will suddenly find its frequency Doppler shifted. Frequency standards stations such as WWV, WWVH, and CHU transmit carriers with atomic-clock grade frequency stability, so they are perfect sources for Doppler monitoring.

“I have been monitoring radio stations for decades, noting sudden changes in signal strength as a means of monitoring space weather events,” says Curtis. “It is only fairly recently (~4 months) that I started to experiment with monitoring the Doppler shift of HF stations. Yesterday’s X-class flare event is by far the most dramatic that I have witnessed thus far.”

Would you like to detect solar flares this way? The HamSCI citizen science program has developed a Personal Space Weather Station specifically for doppler shift measurements. This technique can also be used to study solar eclipses.

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