09/10/2021

Tad Cook, K7RA, Seattle, reports: Sunspot activity increased dramatically this
week.

Over the course of the reporting week, sunspot numbers peaked at 87 on
Wednesday, September 8; the day before, solar flux peaked at 101.2.

The average daily sunspot numbers rose by 14, to 64.6, while the average daily
solar flux increased from 88 to 92.9. New sunspots appeared on September 2 and
September 3, and three more new sunspot groups arrived on September 4. Another
new one appeared on September 8, and on that day the total sunspot area was
1,000 micro-hemispheres.

On September 9, I was shocked to see the daily sunspot number at 124 and the
total sunspot area hit 1,030 micro-hemispheres. I don't believe we've seen
activity like this in nearly 6 years, when the daily sunspot number hit 125 on
September 29, 2015.

We saw similar large total sunspot area numbers last November 25 - 26 - 1,180
and 1,020 micro-hemispheres. Sunspot numbers were 40 and 43 on those days, but
a few days later on November 29 the sunspot number shot to 84.

Both the daily planetary and middle latitude A index reached highs of 14 on
September 8. The averages were 7 and 7.7, down from 9.6 and 10.7 in last week's
planetary and middle latitude readings.

Predicted solar flux seems quite promising, at 100 on September 10 - 11; 98 on
September 12 - 13; 95 on September 14 - 17; 85 on September 18; 88 on September
19 - 23; 90 on September 24 - 28; 88 on September 29 - October 1; 86 on October
2; 90 on October 3 - 6; 92 and 90 on October 7 - 8, and 85 on October 9 - 15.
Flux values are expected to rise to 90 again after October 20.

Predicted planetary A index is 5, 8, and 8 on September 10 - 12; 5 on September
13 - 20; 8 on September 21; 5 on September 22 - October 1; 8 again on October 2
- 3, and 5 on October 4 - 17.

On Sunday September 5, Spaceweather.com[1] reported, "For most of the past 3
years, the sun has been absolutely blank. Today the sun has six sunspot groups.
They're popping up all over the solar disk.

"The sudden profusion of so many sunspots is a sign of strength for young Solar
Cycle 25. The solar cycle is actually running ahead of schedule. NOAA and NASA
predicted that it will peak in the year 2025. Outbreaks like this one support
the idea that solar max could come a year early."

On September 8, Spaceweather.com[2] reported a shortwave blackout over the
Pacific Rim caused by a coronal mass ejection (CME) on September 8 at 1736 UTC.

Here's the most recent forecast[3] from the Space Weather Woman, Tamitha Skov,
WX6SWW, although by now it is a bit out of date.

This is an interesting article[4] about recent solar activity, but it is
plagued with many popups.

Recently in this bulletin we mentioned the US Postal Service issuing stamps
with solar images. This article[5] from June which gives much more detail on
the creation of the stamps.

Sunspot numbers for September 2 - 8 were 33, 33, 68, 66, 80, 85, and 87, with a
mean of 64.6. The 10.7-centimeter flux was 85.8, 83.8, 86.5, 93.3, 99.5, 101.2,
and 100.4, with a mean of 92.9. Estimated planetary A indices were 4, 6, 5, 6,
6, 8, and 14, with a mean of 7. Middle latitude A index was 3, 6, 5, 8, 8, 10,
and 14, with a mean of 7.7.

For more information concerning radio propagation, visit[6] the ARRL Technical
Information Service, read[7] "What the Numbers Mean...," and check out this
propagation page[8].

A propagation bulletin archive[9] is available. For customizable propagation
charts, visit the VOACAP Online for Ham Radio[10] website.

Instructions[11] for starting or ending email distribution of ARRL bulletins
are on the ARRL website.

Share[12] your reports and observations. 

[1] http://www.spaceweather.com/
[2] http://www.spaceweather.com/
[3] https://youtu.be/EndF67TGlnY
[4] https://bit.ly/396UGFf
[5] https://bit.ly/3yRtlkx
[6] http://arrl.org/propagation-of-rf-signals
[7] http://arrl.org/the-sun-the-earth-the-ionosphere
[8] http://k9la.us/
[9] http://arrl.org/w1aw-bulletins-archive-propagation
[10] https://www.voacap.com/hf/
[11] http://arrl.org/bulletins
[12] mailto:k7ra@arrl.net

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