"GEOMAGNETIC DISTURBANCE WARNING ISSUED AT 0713UT/13 JULY 2023 BY THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE.

A glancing CME impact is expected late on 13-July and another CME impact is expected early on 15-July. These impacts present the possibility of geomagnetic storm activity over 13-15 July."

We saw a welcome rise in solar activity this reporting week, July 6-12. Referencing the previous seven days, average daily sunspot numbers rose from 126.1 to 181.9, while average daily solar flux increased from 164.5 to 179.4. On July 13 the solar flux was 202.9, well above the average for the previous seven days.

Geomagnetic indicators did not change much, average planetary A index going from 7.3 to 8.6 and average daily middle latitude A index from 8 to 8.1.

The most active day was July 7 when University of Alaska's college A index was 40.  The middle latitude A index on that day was only 11. The college A index is from a magnetometer in Fairbanks.

What is the outlook for the next month?

Predicted solar flux looks great over the next few days, at 200, 202, 198, 200, and 204 on July 14-18, 202 on July 19-21, 160 on July 22-23, 155 on July 24-25, 160 on July 26-27, 165 on July 28-29, 170 on July 30-31, 165 on August 1-4, 170 on August 5, 175 on August 6-7, 170 on August 8, then 165 on August 9-11, 170 on August 12, 175 on August 13-14, 170 on August 15-17, and 160 on August 18-19.

Predicted planetary A index is 10 on July 14, 5 on July 15 through August 2, then 10, 8 and 5 on August 3-5, then 8, 8, 5, 8 and 8 on August 6-10, 5 on August 11 through the end of the month.

On July 12, Spaceweather.com reported:  

"A new hyperactive sunspot is producing M-class solar flares every few hours. This is causing shortwave radio blackouts around all longitudes of our planet. If current trends continue, an X-flare could be in the offing."

See Spaceweather.com for updates.

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere July 14-20, 2023 from OK1HH.

"Over the past week, we were surprised by two large groups of spots that appeared on the eastern limb of the solar disk.

The first of these, AR3363, emerged in the southeast. Although it remained large, there was nothing significant going on. Its opposite was AR 3372 a few days later, which produced moderate-sized flares almost daily.

In both cases, helioseismic echoes from the sun's far side suggested that it may be the leading edge of a large active region.

But there was no indication that these would be areas with a diametrically different type of activity.

The images of the two groups of spots were large enough to be observed by the Mars rover Perseverance. Because of Mars' position, it saw them a few days earlier than a terrestrial observer. For the record: Perseverance observes the Sun daily, but mainly so that it can tell from the drop in brightness that a Martian dust storm is approaching.

AR3372 activity is increasing, while on July 11 and 12 several M-class solar flares (some with CMEs) have already occurred (X-class flare appeared to be imminent). In particular, it was almost certain that the Earth's magnetic field activity would increase in the following days. The probability of magnetic storms increased significantly as AR3372 rotated more and more toward the Earth."

Carl, K9LA had comments on the OK1HH report from last week.  "There have been many papers in recent years that have looked at the trends in ionospheric parameters over the past decades. Although the changes are small, they do show up in ionosonde data after much math to eliminate solar activity and geomagnetic field activity. These results show both positive and negative trends in the F2 region electron density, likely due to neutral atmosphere dynamics and electrodynamics that could give regional differences.

An interesting paper in 2008 Geophysical Research Letters modeled the increased levels of CO2 (global warming) in the atmosphere versus the impact on the ionosphere.

See: https://bit.ly/3OaThCC

They used 2000 as the baseline with 365 ppmv of CO2, and doubled the amount of CO2 for the year 2100. Their results showed that electron densities in the E and F1 region would increase a couple percent in 2100 while the height of the E region peak would decrease a couple km. In the F2 region, the electron density would decrease by several percent in 2100 while the height of the F2 region would decrease 10 or so km."

Thanks to reader David Moore for this, on aurora hype:

https://bit.ly/44ovzsh

Flare video (with music.)

https://www.youtube.com/watch?v=aghiHieqCZQ

Huge sunspot:  https://bit.ly/44EcqTz

Tamitha Skov reports:  https://youtu.be/nwtCBH04bIg

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 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:

https://www.arrl.org/files/file/Technology/tis/info/pdf/0209038.pdf

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 July 6 through 12, 2023 were 149, 147, 167, 183, 181, 227, and 219, with a mean of 181.9. 10.7 cm flux was 157.6, 161.4, 160.5, 179.2, 190.6, 213.5, and 193.3, with a mean of 179.4. Estimated planetary A indices were 11, 18, 8, 4, 5, 8, and 6, with a mean of 8.6. Middle latitude A index was 11, 16, 6, 4, 6, 8, and 6, with a mean of 8.1.