(3078) Fri 19 Mar 93 2:01 By: Tad Cook To: All Re: ARRL Propagation Bulletin #11 St: ------------------------------------------------------------ SB PROP @ ARRL $ARLP011 ARLP011 Propagation DE KT7H QST DE W1AW Propagation Forecast Bulletin 11 ARLP011 From Tad Cook, KT7H Seattle, WA March 19, 1993 To All Radio Amateurs We are now in month 79 of the current solar cycle 22. Recent projections from NOAA show a continued drop in the solar flux over the next few months, and then starting in August, a modest rise in activity, peaking in April, 1994. This is followed by a decline in activity until we reach the bottom of the solar cycle around early 1997. But given the brief rise in activity, conditions should be better from this summer until November, 1994, when solar flux is back down around the levels for the current month. There was plenty of flare activity to disrupt HF communications last week. The worst days were March 11 and 15, when the Planetary A Index was 32 and 54. Over the next few days there may be some disturbances from Solar Region 7448, which has grown in complexity on Thursday. Coronal holes should be in position to launch more disturbances around March 21 and 27, and April 4 and 12. We have just passed the Spring Equinox, which makes this a great season for HF communications. WWV reported solar flux of 161 for March 12, but this appears to be flare enhanced. The number shown below for that date uses the 1700Z measurement of 151.1, in order to exclude the effect of the flare. Sunspot Numbers from March 11 to 17 were 111, 108, 88, 66, 82, 84 and 82, with a mean of 88.7. 10.7 cm flux was 150, 151.1, 141.5, 136, 131.4, 121.7 and 123.6, with a mean of 136.4. The propagation projection for this week is from Hawaii to Germany. 80 meter propagation should be limited, with a brief opening around 0500 to 0600 UTC. 40 meters should be best from 0400 to 0800 UTC, peaking around 0530. 30 meters should be open from 0330 to 1300 UTC, and again from 1430 to 1700 UTC, with the best times from 0430 to 0730 UTC. 20 meters looks best from 0630 to 1800 UTC, and 17 meters from 1700 to 1930 UTC, and around 0800 UTC. 15 meters should have some openings on most days from 1730 to 1930 UTC, with the best path around 1800 UTC. 12 meters looks marginal, but could have some openings on some days around 1800 to 1900 UTC. The prognosis for 10 meters from Hawaii to Europe does not look good, although on some days there may be an opening for a few hours after the European sunset. /EX --- Opus-CBCS 1.73a * Origin: The Brier Patch *HST/DS* (206) 743-9452 (1:343/5.0) SEEN-BY: 11/2 13/13 101/1 109/25 114/5 123/19 124/1 2107 4115 4210 SEEN-BY: 124/5118 5125 6108 6119 7001 7007 7009 7012 7014 8002 SEEN-BY: 153/752 203/23 209/209 280/1 390/1 393/101 396/1 15