rjr@mgweed.UUCP (Bob Roehrig) (10/02/84)
qst de k9eui hr propagation forecast bulletin nr 40 from arrl headquarters newington ct october 1, 1984 to all radio amateurs bt solar flux data for july through september make a good case for last weeks statement thast the end of solar cycle 21 could be near. the flux high for july was 93. the first 93 of the rising cycle came in february, 1977. the september average, 78, relates to march 1977, in the same way. the weeks low, 79, was last seen in november 1976, when cycle 21 was a mere four months old. if fall dx results thus far have been below expectations, it could be because the qst charts from july on were based on solar flux values between 12 and 17 percent of those actually observed. this condition now seems leikely to apply to the charts in october qst as well. the past week did not bring the rise that had been indicated by new solar activity observed one solar rotation earlier. instead, the solar flux staggered along in the low seventies, then dropped to an eight year low of 79 on the 20th, but no large upswing is expected. rather the prospects are for generally poor conditions through october 3. the beginning of the forecast week should be quite good, but with continuing low maximum useable frequencies. american sunspot numbers for september 20 through 27 were between 0 and 9 with a mean of 3.1 ar
rjr@mgweed.UUCP (Bob Roehrig) (10/08/85)
qst de k9eui hr propagation forecast bulletin nr 40 from arrl headquarters newington, ct october 7, 1985 to all radio amateurs bt the solar flux has been 70 or lower since september 6. the october 6 reading of 66 ties the cycle 21 record low. thus we enter what is normally known as the prime dx season with solar activity so low that even 14 mhz is borderline territory. what little dx there is on 21 mhz is mostly north south in character, and even this is rarely heard on 24 or 28 mhz. prospects for major improvements are not bright. the few active areas on the sun in september should be showing up this week. even a small rise in the solar flux would make a perceptible improvement in 21 mhz propagation and bring at least some north south potential back to 24 and 28 mhz. flux numbers in the high 70s would help a lot this time of year, but there is no basis in sight for predicting this much improvement. a less attractive prediction makes more sense. this september was a time of high geomagnetic activity, a degrading factor likely to be with us again october 10 through 19. we were entering a period of relative quiet at bulletin time, and this could last through about october 9. erratic and frequent ups and downs observed september 13 through 18 are likely to return about october 11 through 19. late october looks somewhat better than the first half, with the 27th through the 29th probably the best of the fall season to date, but improvements if any will be mainly on 14 mhz and lower bands. there can be bursts of high solar activity in the late years of the solar cycle. any tangible evidence of this in prospect will be reported in special bulletins. american sunspot numbers for september 26 through october 2 were between 0 and 3 with a mean of 0.4 ar