On Wednesday, Spaceweather.com reported a new emerging Cycle 25 sunspot in the sun’s Northern Hemisphere, but it was not yet numbered. By the next day (yesterday) it had already faded away into nothingness.
In last week’s bulletin we reported sunspots on just two days, March 8 and 9.
Average daily sunspot number over this reporting week (March 12-18) declined to zero from 3.6, and daily solar flux values barely changed from 70.2 to 70.1. Geomagnetic averages were quiet but higher, with planetary A index changing from 4.4 to 5.9 and middle latitude A index from 3.6 to 4.1.
Predicted solar flux for the next 45 days is 72 on March 20-27, 70 on March 28 until April 4, 72 on April 5-18, 70 on April 19 until May 1, and 72 on May 2-3.
Predicted planetary A index is 8 on March 20-23, 5 on March 24-27, then 8 on March 28, 5 on March 29 until April 5, then 10 and 8 on April 6-7, 5 on April 8-13, then 8, 12 and 8 on April 14-16, 5 on April 17-22, then 12 and 8 on April 23-24, and 5 on April 25 until May 2 and 10 on May 3.
We have been looking forward to the vernal equinox, which occurred at 0350 UTC today, March 20. Of course, depending on where you are, the arrival of spring may have been reported as yesterday, but here we are referring to the date as Friday because of UTC. So that is the same as 8:50 PDT or 11:50 EDT on Thursday.
This is a favorable time for HF propagation, with both the northern and southern hemispheres receiving an approximately equal amount of solar radiation.
Space.com has some of the finer details on the beginning of spring 2020, and an article about sunspots:
Geomagnetic activity forecast for the period March 20 until April 15, 2020 from F.K. Janda, OK1HH:
Geomagnetic field will be
quiet on: April 10
quiet to unsettled on: March (20-26,) 29-30, April 2-5, 7, 11-13
quiet to active on: (March 28, 31, April 1, 6, 8-9)
unsettled to active on: (March 27, April 14-15)
active to disturbed: never
Solar wind will intensify on: March 28, (29-31, April 9, 13)
– Parenthesis means lower probability of activity enhancement.
– The predictability of changes remains lower as there are no indications.
A couple of resources I am finding useful for real time reporting of propagation on various bands, modes and times, from 24 hours ago until present time:
If you would like to make a comment or have a tip for our readers, email the author at email@example.com.
For more information concerning 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/.
Monthly propagation charts between four USA regions and twelve overseas locations are at http://arrl.org/propagation.
Instructions for starting or ending email distribution of ARRL bulletins are at http://arrl.org/bulletins.
Sunspot numbers for March 12 through 18, 2020 were 0, 0, 0, 0, 0, 0, and 0, with a mean of 0. 10.7 cm flux was 69.9, 68.8, 68.1, 70.2, 69.8, 71.6, and 72, with a mean of 70.1. Estimated planetary A indices were 7, 7, 3, 5, 7, 6, and 6, with a mean of 5.9. Middle latitude A index was 7, 6, 2, 3, 3, 4, and 4, with a mean of 4.1.
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