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Last update: Friday, 02-Jun-2023 03:28:47 GMT
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ARLP022 Propagation DE K7RA
QST DE W1AW
ARRL Propagation Bulletin 22 ARLP022 From Tad Cook, K7RA
Seattle, Washington June 2 2023
To all radio amateurs
Average daily solar flux values dropped over the past week, but sunspot numbers were nearly the same, comparing May 25 to 31 to the previous week.
Average daily solar flux declined from 161.2 to 155.3. Geomagnetic indicators were quieter, with average daily planetary A index declining from 17.1 to 7.3, and middle latitude numbers from 14.4 to 7.9.
Predicted solar flux is 160 on June 2, 155 on June 3-4, 150 on June 5-8, 130 on June 9-11, then 135, 140, 143, 145, and 150 on June 12-16, 155 on June 17-20, 150 on June 21-25, then 145, 140 and 135 on June 26-28 and 130 on June 29 to July 8.
Predicted planetary A index is 15, 12, 10 and 8 on June 2-5, 5 on June 6-17, then 22, 15, 12 and 10 on June 18-21, 5 on June 22-24, 12 and 10 on June 25-26, then 5 on June 27-28, then 15, 12, 15, 10 and 8 on June 29 through July 3, then 5 on July 4 through the middle of the month.
"Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere ' June 1, 2023 from OK1HH.
The sun still surprises us, it has been in the habit for billions of years, but we only observe it for a few hundred years. So we have a right to be surprised by what it is doing and what we can observe with instruments on satellites and powerful solar telescopes on Earth, including the largest four-metre one on the island of Maui in Hawaii, which can see the very fine structures of sunspot nuclei.
What's more, we're seeing spots on the far side of the Sun that are so big, they affect the vibration of the whole Sun. But we can only see their structure and predict possible flares after they appear on the eastern limb of the solar disk, which was not at all the case with the current most active AR3315, which did not appear there. It emerged later, thereafter began to grow rapidly.
Conversely, the source of the next big flare was hidden behind the southeastern limb and we only saw the prominence above it.
Meanwhile, the larger groups of sunspots have mostly moved to the western half of the solar disk. A large coronal hole in the southern hemisphere now crosses the central meridian. This increases the likelihood of geomagnetic disturbances starting on June 2."
Mike, AK7ML wrote:
"I recall in a movie about Pearl Harbor that they could not reach Hawaii from stateside on HF and then they sent the message by cable telegraph in routine status so Pearl was not informed of the attack in time.
For years I have been able to work Australia in the morning and now it is Indonesia that is workable instead!'D
I've added this resource to the text appearing at the bottom of every bulletin, from September 2002 QST:
I was sad to learn that old friend Chip Margelli, K7JA became a silent key on May 25. Chip was from the Seattle area, and first came to my attention when he became proficient in the Japanese language during high school, then specialized in running JA stations at the old W7RM contest station on Foulweather Bluff in Puget Sound, built by Rush Drake. At one time he may have been the most famous American ham in Japan, or so I heard at the time.
Send your tips, reports, observations, questions and comments to email@example.com. 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 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 .
Also, check this article from September, 2002 QST:
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 May 25 through 31, 2023 were 121, 127, 125, 119, 153, 144, and 147, with a mean of 133.7. 10.7 cm flux was 152.1, 149, 156.9, 151.3, 154.4, 162, and 161.4, with a mean of 155.3. Estimated planetary A indices were 11, 6, 4, 11, 4, 5, and 10, with a mean of 7.3. Middle latitude A index was 11, 6, 5, 11, 5, 6, and 11, with a mean of 7.9. NNNN
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