Possible detection of solar Type-II/III radio emissions on kiwisdr

During a solar coronal mass ejection, the ejecta generates radio emissions as it plunges through the suns chromosphere and corona. These emissions can be received on earth. There are different types of radio emissions, shown in the spectrogram examples on this page:


Early in the year, I observed a noise pattern in my kiwisdrs spectrogram that coincidentally happened at the same time as a solar flare with CME. I was sceptical, so I haven't thought further about this.

On June 9th 2021, I saw the same pattern again, at the same time of a CME associated to a C3.8 LDE flare, with officially confirmed type-II radio emission.

I was still sceptical if it was really what I was seeing on my kiwisdr.

Here is a spectrogram of the event. Note that I have set the spectrogram very sensitive (low dynamic range) for the purpose of showing background noise. So DSL and PLC noise from more than 50 meters away can be seen. Also I have some LC filters installed, to prevent receiver saturation from strong broadcast stations. WF-rate 1 Hz. Suspected radio emission is circled red:

Below 5 MHz no emission was recorded (on a separate kiwisdr with different filters). But the signal would be attenuated by the ionospheric D-layer anyway, so it can't reach earth surface.

Now, today there was a powerful X1.59 flare. And my kiwisdr shows again this pattern. This time also with a distinctive radio blackout, as expected from a X-class flare.




  • I've spotted similar on the VK5ARG KiwiSDR:

    At first I thought there was some issue with the site, or someone had driven a RF-noisy car up to the antenna, but It was also visible on the Australian Bureau of Meteorology's Learmonth Spectrograph.


    Mark VK5QI

  • Cool! Must be my best DX so far.

    But you were on the night side during the flare, right?

    I think the x-rays caused a significant absorption of the solar radio burst in the shortwave spectum on the dayside.

  • This was in the middle of the day, and it was a different solar radio burst to what you saw (May 22nd 2021).


    Mark VK5QI

  • If you don't see it, click in the middle of the large white space of Mark's message to see the copied tweet. That's what I had to do (another forum bug no doubt).

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