Contesting as the Solar Indices Plummet (Part IV)

by Fred Laun, K3ZO

Well, the 2003 CQWW SSB and CW SS Contests are now history. How did my predictions hold up?

In my article in the October Newsletter I did say: "October 1992 looked like a good candidate [for comparison with this fall's conditions - ed.] but just about the time the CQWW was arriving the solar flux suddenly shot up to 225. (We could always hope that history would repeat itself, of course, and that the solar flux would suddenly increase during this year's CQWW -- wouldn't THAT be great?)".

As we now know, hope became reality. During CQWW SSB the SFI hit 222 on its way up to an eventual high of 298. By the time the CWSS came along it was still up around 249.

Solar scientists have been marveling at the flare production of monster sunspot 10486, which produced several massive X flares, including two that were among the strongest ever recorded since solar measurements began to be made. Some of these scientists have even ventured that this activity may portend fundamental changes in the Sun's behavior. However, as we have seen, in October 1992 there was a similar burst in activity as the cycle moved downward.

At any rate, with this activity fresh in our minds, I would like to devote this month's column to a discussion of recent ob-served propagation conditions.

When spot 10486 and sister spot 10484 first made their presence known to us, they had not yet begun to eject massive amounts of material, but their effects on the Sun's "steady state" output had already caused the solar flux to ratchet up substantially.

In one week the SFI moved from a value of about 90 to a value above 200. Fortuitously, the CQWW took place while this high SFI value existed but before the activity had much negative effect on the Earth's geomagnetic field. This had the result of increasing the MUF so that 10 meters was much better than I had predicted, without initiating geomagnetic storming which would have the effect of shutting down polar paths. Indeed, from the contest results I have seen thus far, "black hole" inhabitants W9RE and N9RV enjoyed generally excellent conditions on 10 and 15, which could not have happened had conditions been massively disturbed.

I did notice that atmospheric absorption increased on the lower bands, particularly the first night on 160. It was a real chore even to break through to stations in the Caribbean, not to mention Europe. However, I found conditions on 80 to Europe OK the first night and really quite good the second night, and conditions to Europe on 40 to be good both nights.

The SFI has sort of a flywheel effect on the ionosphere, so that when the Solar Flux has been elevated for a long period of time, the MUF remains high even when the Sun is not shining directly on the patch of ionosphere in question. Not so with sudden massive spikes in the SFI. Remember, until just before the CQWW Phone Contest, the SFI had been hanging around 90 to 110 for weeks. So when the SFI suddenly jumped up over 200, the MUF was nice and high while the Sun was shining, but as soon as it went down, the MUF plummeted like a rock. This had the effect of closing 20 to Europe -- except for some EA's and I's -- very shortly after 15 had closed to Europe. It was concerning this facet of propagation that I made a serious error in not hitting 20 hard at sunrise, at the beginning of the 20 meter European opening. I will keep this in mind for the CW end of the contest!

We did have a solar flare during CQWW, which caused a blackout on most bands for stations on the sunlit portion of the Earth at the time the blackout hit. It occurred at 1745 UTC Sunday according to Jeff, N8II. I was running Europeans on 15 at the time and I recall noticing that the surrounding QRM, which had been running S9+ for some time, suddenly faded away to nothing. I thought I had finally cleared myself a hole in the band! The stations calling me were not as strong but I could hear them fine and I continued my run all the way through the blackout. Apparently the blackout was worse for stations in tropical areas, as I heard complaining from the Caribbean.

We had another flare during CW SS, on Sunday at 1717 UTC. This time I really noticed it as I was running on 20 when suddenly all the signals around the frequency just faded away. I went looking to see if I could find anyone, and found K3DI who I still needed and worked Dick. Then I heard Marty, K2PLF, who I had already worked. Otherwise, dead silence on the whole 20 meter band. Curiously, the experts say the flare occurred at 1725 UTC, but by then the bands were already long dead. Can it be that there is something even faster than the speed of light that affects the ionosphere?

Just after a major flare signals often drop out, but in half an hour or so the bands generally begin to return to normal. It takes a couple of days before the principal products of the Sun's belch hit Earth's geomagnetic field. There was a massive solar flare at 1110 UTC on October 28, and another, a little less potent, followed within a day. So on October 29 when I got home from the Over the Hill lunch that day, a major aurora was already in progress. I got on 2 meters at 1937 UTC and immediately worked a station in the Nashville, TN area, pretty far south for aurora. My next QSO was with Bob, W4MYA who, despite his being close enough so that he is always S9+ with me on 2 meter CW, was that day 100 percent aurora hiss with my beam to the North.

In my next installment, I will discuss how propagation is affected on the various bands during a major geomagnetic storm. With normal conditions gone many hams give up, but propagation during such storminess can be fascinating, as I will illustrate next month.