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Propagation Forecast Bulletin 12 ARLP012-24
SB PROP @ ARL $ARLP012 ARLP012 Propagation de K7RA ZCZC AP12 QST de W1AW Propagation Forecast Bulletin 12 ARLP012 From Tad Cook, K7RA Seattle, WA March 22, 2024 To all radio amateurs SB PROP ARL ARLP012 ARLP012 Propagation de K7RA Over March 14-20, new sunspot groups emerged every day except March 19. March 18 had two, and each of the other days saw one new sunspot group. It is now Spring in the Northern Hemisphere which is favorable to HF conditions, and solar and geomagnetic numbers both show improvement. Average daily sunspot numbers rose from 82.3 to 94.3, and average daily solar flux jumped from 130.4 to 153.3. Geomagnetic indicators were very quiet, with the average daily planetary A index dropping from 8.9 to 5.9, and middle latitude numbers from 7 to 5. Here is the outlook for the next month. Predicted solar flux is 180 and 178 on March 22-23, 174 on March 24-25, then 176 on March 26-27, 178 on March 28, 165 on March 29-30, 160 on March 31, 155 on April 1-3, then 158 on April 4, 160 on April 5-6, then 162, 155, 150, and 145 on April 7-10, 148 on April 11-12, then 152, 155, 160, 162, 165 and 160 on April 13-18, then 155 on April 19-20, 152 on April 21, 160 on April 22-23, then 162, 165, 165 and 160 on April 24-27, and 155 on April 28-30. Predicted planetary A index is 12, 5, 16, 18 and 8 on March 22-26, then 5, 5 and 8 on March 27-29, 5 on March 30 through April 2, then 15, 12 and 12 on April 3-5, 5 on April 6-8, 8 on April 9-11, then 5 on April 12-23, 10 on April 24-25, and 5 on April 26-29. Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere - March 21, 2024, from F.K. Janda, OK1HH: "Solar activity on average continues to increase toward the Solar Cycle 25 maximum. This included a shower of protons that came from the admittedly smaller in X-ray intensity but primarily long-lived flare on the morning hours UTC of March 15. The particle density peaked a day later when the proton event reached S1. High polar cap absorption of radio waves was recorded at the same time. "The geomagnetic field remains mostly calm, with the occurrence of short active intervals. An increase in geomagnetic activity was expected after the eruption of 17 March. A partial CME halo was observed and ejected particles were expected in the vicinity of the Earth first on 20 March, then on the evening of 20 March, and then on the morning of 21 March. The result was an increase in MUF already in the forenoon UTC. An increase in the Earth's magnetic field activity occurred in the afternoon. "The new sunspot group AR3615, which emerged in the southeast of the solar disk, although not yet large, has a complex magnetic structure. This configuration increases the probability of magnetic reconnection during a solar flare. Especially if an X-class solar flare occurs, the probability of CME will increase." Angel Santana, WP3GW wrote about conditions on March 16 in an email: "With much expectation worked the Russian DX contest on SSB, but then noticed rough conditions, so bad that after 1600 UTC signals were gone, not seen on my radio. After 1730 UTC saw them come back but conditions were still bad. "Next day did the BARTG RTTY contest after 1430 UTC and fared better. "Did it have to do with one of the six sunspots last week? Hope prop is good in a week from now." I replied that according to Spaceweather.com, departing sunspot AR3599 blasted protons toward Earth on March 14, causing a polar cap absorption event on March 16. The ionizing effect of the protons absorbed radio signals inside the arctic circle. Nasa Space Flight article about VLA detection of radiation above sunspots: https://bit.ly/4cDDref Article about Radio Blackout: https://bit.ly/3ILT6KH From Dr. Tamitha Skov, WX6SWW: "Dear Tad, "Recently our Sun gave us a surprise when a solar storm we thought would be a glancing blow, actually hit us pretty hard. That was back on March 3rd and some gorgeous aurora shows were seen in Tasmania and Australia (see my forecast from that week for some amazing pictures: https://youtu.be/2nWLAYL01FA). "Here we are several weeks later with yet another glancing blow set to hit us midday March 20th. The official forecast is calling for a weak impact, but our recent experience has left me wondering: Are we are going to make the same mistake twice? "These are the kinds of dilemmas that make space weather such a tough field today. Compared to terrestrial weather, there are so many things we simply cannot foresee. "Turning to the forecast, big flare activity is beginning again thanks to old Region 3590 rotating back into view along with some new players as well. Amateur radio bands are getting noisier and radio blackouts are resuming on the daylight side of Earth. Of course, the big story is the solar storm coming towards us. Will it be relatively mild at mid-latitudes, as the predictions suggest? This time, I'm not so sure. Either way, I will remain on the lookout. "Cheers, Tamitha." Here is her latest video report: https://youtu.be/O6vZDFaBfrc Send your tips, reports, observations, questions, and comments to k7ra@arrl.net. When reporting observations, don't forget to tell us which mode you were operating. For more information concerning shortwave radio propagation, see http://www.arrl.org/propagation and the ARRL Technical Information Service web page at, http://arrl.org/propagation-of-rf-signals . For an explanation of numbers used in this bulletin, see http://arrl.org/the-sun-the-earth-the-ionosphere . An archive of past propagation bulletins is at http://arrl.org/w1aw-bulletins-archive-propagation . More good information and tutorials on propagation are at http://k9la.us/ . Also, check this QST article about Solar Indices: https://bit.ly/3Rc8Njt Instructions for starting or ending email distribution of ARRL bulletins are at http://arrl.org/bulletins . Sunspot numbers for March 14 through 20 2024 were 88, 49, 67, 86, 127, 123, and 120, with a mean of 94.3. 10.7 cm flux was 127.1, 129, 144.1, 151.3, 177.4, 168.9, and 175.5, with a mean of 153.3. Estimated planetary A indices were 8, 8, 3, 3, 6, 9, and 4, with a mean of 5.9. Middle latitude A index was 7, 8, 3, 2, 5, 7, and 3, with a mean of 5. NNNN /EX
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