[SFDXA] ARLP036 Propagation de K7RA

Fri Sep 8 12:10:08 EDT 2023

> SB PROP @ ARL $ARLP036
> ARLP036 Propagation de K7RA
> 
> ZCZC AP36
> QST de W1AW  
> Propagation Forecast Bulletin 36  ARLP036
> From Tad Cook, K7RA
> Seattle, WA  September 8, 2023
> To all radio amateurs 
> 
> SB PROP ARL ARLP036
> ARLP036 Propagation de K7RA
> 
> At 0046 UTC on September 8, the Australian Space Weather Forecasting
> Centre issued this alert:
> 
> "A solar filament erupted from the north east quadrant of the Sun on
> 07-Sep. Event modeling shows an edge of the associated north east
> directed CME may graze the Earth's magnetosphere on 10-Sep.
> INCREASED GEOMAGNETIC ACTIVITY EXPECTED DUE TO CORONAL MASS EJECTION
> FOR 10 SEPTEMBER 2023."
> 
> Eight new sunspot groups emerged this week, one on September 2, two
> on September 3, two more on September 4, and one each on September
> 5-6, followed by another on Thursday, September 7.
> 
> Average daily sunspot number was up, from 78.7 to 95.4, while
> average daily solar flux was less, from 140.9 to 137.6.
> 
> Geomagnetic activity was higher. On September 2 the planetary A
> index was 38, when Earth moved through a high speed solar wind. In
> Alaska, the college A index at Fairbanks was 59.
> 
> Average daily planetary A index increased from 7 to 15.4, and
> average middle latitude A index rose from 8.9 to 16.3.
> 
> Predicted solar flux is 155, 158 and 155 on September 8-10, 150 on
> September 11-16, then 155, 150, 155 and 150 on September 17-20, 145
> on September 21-22, 150 on September 23-24, 145 on September 25, 140
> on September 26-27, 135 on September 28-30, then 130, 135, 130 and
> 135 on October 1-4, then 140 on October 5-6, then 135, 135 and 140
> on October 7-9, 145 on October 10-11, 150 on October 12-13, then
> 155, 150, 155 and 150 on October 14-17.
> 
> Predicted planetary A index 10 and 12 on September 8-9, 8 on
> September 10-13, then 5, 8, and 12 on September 14-16, 8 on
> September 17-18, 5 on September 19-22, 12 on September 23, 5 on
> September 24-27, then 8, 12, 5 and 12 on September 28 through
> October 1, then 12, 10, 12 and 10 on October 2-5, and 5 on October
> 6-10, then 10, 8 and 12 on October 11-13, and 8 on October 14-15,
> and 5 over the following week.
> 
> I observed interesting 12 meter propagation using FT8 on September
> 4, at 1745 UTC with https://pskreporter.info/pskmap.html in which my 
> signal was only received over a narrow 300 mile band hugging the East 
> Coast from Maine to Florida, all signal reports between 2200 to 2500 
> miles away, nowhere else.
> 
> Three hours later at 2045 UTC, the reports along the coast expanded
> to 600 miles, 2000 to 2600 miles wide.
> 
> Later at 2300 UTC it was the same pattern, but a 200 mile band,
> 2300-2500 miles wide.
> 
> The next day at 1700 UTC it was an arc from Virginia to South Texas,
> 1700 to 2300 miles. At 1715 UTC it drifted to coverage of 1750 to
> 2600 miles.
> 
> Before FT8 and pskreporter, there was no practical way for me to
> observe any of this. Who knew?
> 
> Rick Cochran, WO8L wrote:
> 
> "So, despite all of the indicators being pretty good, why are the
> bands so terrible?
> 
> "In the nearly 60 years I've been a ham this Sun cycle has
> consistently been a dud compared to past cycles, especially during
> the day.
> 
> "So many of us would like to know why."
> 
> I replied:
> 
> "Good question. You aren't the only one to ask."
> 
> There is a theory that carbon in the atmosphere or a warming climate
> contributes to this, but I do not understand the mechanism. K9LA
> told me that models do not support this, but at the moment I cannot
> recall what those models are. This issue was discussed in previous
> bulletins.
> 
> Another theory is that this is a perception issue related to the
> widespread adoption of FT8, in which users of traditional modes see
> less activity on CW and SSB and perceive poorer propagation as a
> result.
> 
> Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
> Ionosphere - September 7, 2023, from F.K. Janda, OK1HH:
> 
> "In late August, as AR3413 approached the northwestern limb of the
> solar disk, its eruptive activity began to increase, even though its
> size and magnetic configuration did not suggest it. However, we
> observed it at a very low angle, so we may have missed details.
> 
> "Either way, it was the source of several C- and M-class flares, at
> least two of which (on August 30 and September 1) ejected CMEs. Both
> hit the Earth triggering a G2 class geomagnetic storm. For shortwave
> propagation, this meant a significant improvement and increase in
> MUF in the positive phase of the disturbance on 2 September
> 0900-1300 UTC, followed by a deterioration for the next few days.
> 
> "AR3413 meanwhile, continued with increased eruptive activity on the
> Sun's far side, including a massive CME on 5 September, but it no
> longer affected the Earth. It merely 'ripped off the tail' (a
> disconnection event) of comet Nishimura (C/2023 P1), which is
> approaching the Sun. Its closest approach will be on September 17.
> 
> "A relative improvement in shortwave propagation did not occur until
> September 5, with a jump in solar wind speed at 1439 UTC. Meanwhile,
> active region AR3421 began to grow significantly around the central
> meridian.
> 
> "The magnetic configuration points to the possibility of
> geoeffective flares. This was followed by the growth of other active
> regions in the northeast of the solar disk, so that solar activity
> remains elevated. Since we expect the Earth's magnetic field to calm
> down, shortwave propagation conditions should gradually improve.
> Seasonal changes as the equinoxes approach will also contribute to
> this."
> 
> The Autumnal Equinox in the northern hemisphere is just two weeks
> away.
> 
> Here is a solar cycle prediction:
> 
> https://bit.ly/45Gxb1n
> 
> Nice video, once you get past the ads:
> 
> https://www.dailymotion.com/video/x8nub71
> 
> A "Solar Orbiter EUI" video from Max White, M0VNG and the European
> Space Agency:
> 
> https://bit.ly/44JG2hr
> 
> Send your tips, reports, observations, questions, and comments to
> k7ra at arrl.net . When reporting observations, don't forget to tell us
> which mode you were operating.
> 
> Also, check this article from September, 2002 QST:
> 
> https://bit.ly/3Rc8Njt
> 
> 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 August 31 through September 6, 2023 were 77, 83,
> 77, 79, 100, 121, and 131, with a mean of 95.4  10.7 cm flux was
> 139.9, 135.8, 131.2, 130.5, 136, 142.9, and 147.1, with a mean of
> 137.6. Estimated planetary A indices were 6, 12, 38, 25, 8, 11, and
> 8, with a mean of 15.4. Middle latitude A index was 8, 15, 25, 28,
> 14, 14, and 10, with a mean of 16.3.
> NNNN
> /EX