rjr@mgweed.UUCP (Bob Roehrig) (06/12/84)
qst de k9eui hr propagation bulletin nr 24 from arrl headquarters newington ct june 11 1984 to all radio amateurs bt from early january through late may, the sun was more active than would have been expected so late in the solar cycle, but it lost most of its spots in the last two weeks. the solar flux was 66 points lower on may 27 than on april 29, one solar rotation earlier, and down to 90 on june 10. this was its lowest level since january 10. the best part of this picture is that the effekts of lower solar flux and lower sunspot numbers are minimal at this season. if the sun should recover somewhat in the autumn, it will do more for northern hemisphere dx then than now. more on this prospect will be given in late summer bulletins. a portion of the sun with that flux peak of 140 on may 21 will come into view about june 14. for the week, it is expected that hf propagation will be fair to good june 11 to 13, but recurrent geomagnetic disturbances are due june 16 through 21. sporadic e layer ionization increases gradually in june, helping to keep things happening on 21, 28, 50 and possibly 144 mhz almost regardless of flux or sunspot numbers. american sunspot numbers for may 31 through june 6 were between 24 and 48 with a mean of 37.3. ar
rjr@mgweed.UUCP (06/18/85)
qst de k9eui hr propagation forecast bulletin nr 24 from arrl headquarters newington ct june 16, 1985 to all radio amateurs bt as discussed in last weeks bulletin, the solar flux curve is beginning another downward trend. numbers have been close to those of 27 to 28 days ago except that since june 11th the decline has been more rapid. the flux number for june 16 was 78, ten points below that for may 19, when the sun was in a similar position with respect to the earth. flux values near the quiet sun level are expected in the last few days of june. the effects of lower solar activity are minor in the summer months. skip tends to be longer on the lower amateur bands as solar activity declines. on 21, 28 and 50 mhz the early summer sporadic e ionization produces almost daily short skip, over 400 to 1300 miles, depending on the band and on the ionization density. the latter reaches its peak in late june and early july. watch 144 mhz for e skip opportunities this season. the lower solar activity currently makes for less disturbance of the earths magnetic field, and this is good for nearly all amateur communications over other than local distances. undoubtedly, summer is the season for increased thunderstorm activity, and higher noise levels are observed on all frequencies much of the time. storm noise can be propagated over long distances on the lower frequencies. storm static is essentially a local phenomenon on frequencies above the muf at the time. american sunspot numbers for june 6 through june 12 were between 31 and 59 with a mean of 40.3 ar