Many solar flares and CMEs occurred over the reporting week (March 24-30) but with glancing blows and near misses, it wasn’t reflected in the geomagnetic indicators until Thursday, the last day in March.
The Planetary A index reached a high for the reporting week of 19 on March 27. Average daily planetary A index rose by a modest amount from 6.3 to 10.
Average daily sunspot number rose from 33.4 to 80.1, while solar flux went from 99.9 to 132.7.
The rising solar activity brought us a tremendous amount of 10 meter coverage. Every day I have received reports from all over North America from operators hearing my K7RA/B propagation beacon on 28.2833 MHz.
Predicted solar flux is 150, 145, and 130 on April 1-3, 115 on April 4-5, 110 on April 6-8, then 118, 115, and 110 on April 9-11, 105 on April 12-14, 108 on April 15, 105 on April 16-19, 110 on April 20-21, 115 on April 22, 125 on April 23-26, then 123, 118 and 118 on April 27-29, then 108 on April 30 through May 2, 112 on May 3, 115 on May 4-6, and 112 on May 4, then dropping to 105 through the middle of May.
The predicted planetary A index is 32, 10, 15 and 10 on April 1-4, 819, on April 5-6, 5 on April 7-19, 10 on April 20-21, then 5, 15 and 10 on April 22-24, then 5 on April 25-29, 12 and 8 on April 30 and May 1, and 5 0n May 2-15.
A report from F.K. Janda, OK1HH: "We have a week of somewhat wilder development behind us. Its first indication were two sunspot groups on the northeastern limb of the solar disc on March 24. The second of them, region 2976 was larger.
"Region 2975 had a more complex magnetic structure and grew gradually. A proton solar flare was observed on March 28 at 1129 UTC, accompanied by a significant increase in proton levels. And above all, it was followed by a CME heading to Earth!
"Exactly as predicted, the arrival of the CME caused a geomagnetic disturbance on March 31. Its positive phase of development was accompanied, especially in the UTC morning hours, by a significant improvement in the shortwave propagation conditions on a global scale.
"Another solar flare was observed in the same area on March 30 with a maximum at 1737 UTC. Although X-ray levels rose more than on March 28, followed by CME again (albeit weaker, at 1823 UT), there is no expectation that it would be followed by a similar increase in geomagnetic activity."
Angel Santana, WP3GW, of Trujillo Alto, Puerto Rico wrote: “Conditions were decent for the contest last weekend. Ten meters was as good as last October but propagation is still improving, as stations were as high at 28.6 MHz, but on a great season stations would be heard beyond 29 MHz. With the new radios that have spectrum analyzers you can view this. On Sunday at 1420 UTC contacted a few European stations and even a 4X.
When I went to 15/20 meters, I had 85 percent success in contacting the stations. Overall, I worked 324 stations and 64 DXCC entities.
"And there are a few stations from Spain on 10 meters at 2000 UTC, which is their local 10 PM. Really big signals. Cycle 25 is definitely rising."
LA4LN reports 6 meter TEP activity: "I see that stations in southern Europe are reporting contacts with southern Africa and South America, across the magnetic equator.
"Likewise,US stations are making TEP contacts with stations in South America across the magnetic equator, with no F2 propagation possible on 50 MHz at this time, with an insufficient SFI (Solar Flux Index) for 50 MHz F2 propagation.
Seeing more TEP 'heard & worked' between southern Europe and southern Africa on the 6 meters band, across the magnetic equator via Dxmaps.com.”
I often see references to the "magnetic equator" but did not know what it was. This gives a good explanation: https://bit.ly/38nV2u1
More from LA4LN: "In last week’s bulletin you comments from N0JK speculating about the first F2 openings on 50 MHz in the Solar Cycle 25.
"It must be mentioned that the SFI has been near 100 (he reported 95), and this is most likely too low SFI to cause F2 propagation on 50 MHz, according to my experience.
"Instead, during the last few weeks I've seen numerous reports of TEP (Trans Equatorial Propagation) on 50 MHz, with radio amateurs in mainly the southern states of USA working South America – and with radio amateurs in southern Europe working southern Africa and South America.
"It is important to note that the TEP is aligned over the magnetic equator on Earth (not aligned over the geographic equator). TEP is well described in the ARRL literature."
We normally get our 10.7 cm solar flux staight from the source, the DRAO observatory in Penticton, British Columbia: https://bit.ly/3Dur7f0. But since March 18, there has been no new data, so we rely on NOAA as a secondary source, which is why we have recently presented solar flux numbers that are not resolved to 0.1 but instead are from this source, which is also our source for daily sunspot numbers: https://services.swpc.noaa.gov/text/daily-solar-indices.txt. DRAO Penticton has not answered any e-mail inquiries or phone calls, so we wait.
Some of the interesting articles and images this week:
NN4X sent a Pskreporter map showing his 10 meter signal at 1710 UTC on March 29 being received all around the world, including South Africa, Europe, Southeast Asia, South America and across North America. That was just one of many, many 10 meter reports this week.
An exciting new report from Dr. Tamitha Skov, WX6SWW: https://youtu.be/SVbKQmjkqTc
For more information concerning shortwave radio propagation, see http://www.arrl.org/propagation and the ARRL Technical Information Service 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/.
Instructions for starting or ending email distribution of ARRL bulletins are at http://arrl.org/bulletins.
Sunspot numbers for March 24 through 30, 2022 were 44, 50, 48, 97, 125, 124, and 73, with a mean of 80.1.. 10.7 cm flux was 112, 112, 119, 130, 156, 149, and 151, with a mean of 132.7. Estimated planetary A indices were 9, 10, 7, 18, 10, 8, and 8, with a mean of 10. Middle latitude A index was 6, 3, 6, 11, 4, 7, and 6, with a mean of 8.1.