Seemingly weak SFI to MUF correlation

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Seemingly weak SFI to MUF correlation

Postby Gorbash » Fri Oct 31, 2003 7:52 pm


After many years of hf hamming and casually correlating propogation conditions with space weather indices, I'm still uncomfortable with the relationship between SFI and MUF.

Specifically, when the Solar Flux rises to higher values - say 200 and above, it seems to me that the MUF often fails to follow it upwards as much as I would expect. Having now operated through four cycle peaks, and enjoyed 10 and 6 meter f2 through each peak, I have a sense of what higher flux should bring. The issue arises for me when the flux rises to a high value off peak, as it is now, and conditions on 10 and 6 don't seem to reflect the high values of flux.

I think I understand the impact of geomagnetic storming and so expect periods of high K and A indices to be poor periods of hf propogation - as exists right now. On the other hand, when the flux stays very high and the k index drops to 2 or less, it seems to me that the MUF should rise to 30 or 40 or even 50 Mhz since that is the set of conditions that allow high MUFs at solar maximums.

What's happening under these conditions? Do high flux levels need to persist for extended period of time before the MUF rises? Or do stormy conditions need to abate for an extended time period before the the MUF rises? Or is there another explanation?



PS: Couldnt' see any aurora last night from Mukilteo. Conditions seemed right but no go. Great web page and thanks for the discussion board.

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