Subj : The K7RA Solar Update To : QST From : ARRL de WD1CKS Date : Fri Sep 03 2021 13:18:34 09/03/2021 Tad Cook, K7RA, Seattle, reports: Solar activity is on the upswing this week. Average daily sunspot numbers increased from 21.7 to 50.6, with a high of 77 last Saturday, September 28. Average daily solar flux rose from 78.5 to 88. Average daily planetary A index increased from 4.7 to 9.6, and average daily middle latitude A index went from 5.7 to 10.7. Geomagnetic activity peaked August 27 - 28 due to a coronal mass ejection. New sunspot regions appeared on August 26 and 27, and on September 2 Spaceweather.com[1] reported, "New Sunspot, Rapidly Growing" to announce the emergence of AR2863. Predicted solar flux looks promising, particularly after mid - September, at 85 and 82 on September 3 - 4; 80 on September 5 - 6; 78 on September 7; 75 on September 8 - 10; 80 on September 11 - 14; 85 on September 15; 90 on September 16 - 30; 85 on October 1, and 80 on October 2 - 10. Flux values rise to 90 again after October 12 in this forecast from September 2. Predicted planetary A index is 8, 5, 10, and 8 on September 3 - 6; 5 on September 7 - 10; 10 and 8 on September 11 - 12; 5 on September 13 - 20; 8 on September 21; 5 on September 22 - 25; then a big jump to 25, 8, 18, 8, and 12 on September 26 - 30, back to 5 on October 1 - 7, and then 10 and 8 on October 8 - 9. Here's the geomagnetic activity forecast for September 3 - 29, from F.K. Janda, OK1HH. The geomagnetic field will be: o quiet on September 7 - 8, 10, 14 - 15, 17 - 18, 28 - 29 o quiet to unsettled on September 4 - 5, 13, 16, 19, 22, 25, 27 o quiet to active on September 3, 6, 9, 11 - 12, 20 - 21, 26 o unsettled to active on September 23 ( - 24) o active to disturbed - nothing predicted Remarks: * Parentheses mean lower probability of activity enhancement. * The situation is confusing, the configuration of active regions and coronal holes is variable, so it's not possible to make a reasonably reliable forecast. This occasionally happens before solar activity rises. The autumnal equinox will be on Wednesday, September 22, in the Northern Hemisphere, always a welcome event for HF propagation. Solar flux is forecast to be higher at that time, also a good sign. Sunspot numbers for August 26 - September 1, 2021 were 47, 73, 77, 44, 41, 37, and 35, with a mean of 50.6. The 10.7 centimeter flux was 88.6, 89.5, 89.9, 88.7, 90.6, 84.4, and 84.2, with a mean of 88. Estimated planetary A indices were 6, 20, 14, 8, 7, 7, and 5, with a mean of 9.6. Middle latitude A index was 6, 19, 17, 9, 9, 9, and 6, with a mean of 10.7. For more information concerning radio propagation, visit[2] the ARRL Technical Information Service, read[3] "What the Numbers Mean...," and check out this propagation page[4]. A propagation bulletin archive[5] is available. For customizable propagation charts, visit the VOACAP Online for Ham Radio[6] website. Instructions[7] for starting or ending email distribution of ARRL bulletins are on the ARRL website. Share[8] your reports and observations. [1] http://www.spaceweather.com/ [2] http://arrl.org/propagation-of-rf-signals [3] http://arrl.org/the-sun-the-earth-the-ionosphere [4] http://k9la.us/ [5] http://arrl.org/w1aw-bulletins-archive-propagation [6] https://www.voacap.com/hf/ [7] http://arrl.org/bulletins [8] mailto:k7ra@arrl.net --- þ Synchronet þ Whiskey Lover's Amateur Radio BBS .