SB PROP @ ARL $ARLP031
ARLP031 Propagation de K7RA

ZCZC AP31
QST de W1AW
Propagation Forecast Bulletin 31 ARLP031

From Tad Cook, K7RA

Seattle, WA August 4, 2023
To all radio amateurs

SB PROP ARL ARLP031
ARLP031 Propagation de K7RA

The Australian Space Weather Forecasting Centre issued a geomagnetic disturbance warning at 0233 UTC on August 3.

"Two recent coronal mass ejections (CMEs) are expected to impact
Earth on UT day 05-Aug, with the second possibly arriving early
06-Aug. G0-G1 geomagnetic conditions may be expected on 05-Aug, with
a chance for isolated periods of G2 towards the end of the UT day on
05-Aug. Geomagnetic storm conditions may persist over 06-Aug."

Solar activity was up during this reporting week, July 27 through
August 2.

Average daily sunspot numbers increased from 128.1 to 154.3, but
average daily solar flux was about the same as last week, moving
just from 172.2 to 173.

Geomagnetic indicators were quiet, with average daily planetary A
index shifting from 11 to 8.3, while middle latitude numbers went
from 11.1 to 9.3.

Predicted solar flux is 160 on August 4-5, 162 on August 6, 164 on
August 7-8, 162 and 160 on August 9-10, 168 on August 11-12, 170 on
August 13-16, 172 on August 17-18, then 170 and 168 on August 19-20,
170 on August 21-22, 172 on August 23, and 170 on August 24-27, then
165 on August 28-31, then 168, 170, 168, 165, 168, and 165 on
September 1-6, 168 on September 7-8, and 170 on September 9-12.

Predicted planetary A index 15, 26, 15 and 8 on August 4-7, 5 on
August 8-10, 8 on August 11-12, 5 on August 13-25, then 12 and 10 on
August 26-27, and 5 on August 28-31, 12 and 10 on September 1-2, 5
on September 3-5, 10 on September 6, 8 on September 7-8, and 5 on
September 9-17.

No report from OK1HH this week as he vacations in the mountains in
Europe.

See https://bit.ly/44Tw4e2 for an image of him on vacation
previously.

Here are reports from two of his colleagues at Czech observatories.

"Solar activity forecast for the period August 4-10, 2023.

Activity level: mostly low to moderate
X-ray background flux (1.0-8.0 A): in the range C1.1-C2.5
Radio flux (10.7 cm): a fluctuation in the range 155-185
Events: class C (2-15/day), class M (0-3/day), class X (0-2/period),
proton (0-1/period)
Relative sunspot number (Ri): in the range 124-220

Martina Pavelkova RWC Prague, Astronomical Institute, Solar Dept.,
Ondrejov, Czech Republic"

"Geomagnetic activity forecast for the period August 4-10, 2023

Quiet: Aug 3, 5-8
Unsettled: Aug 4-5, 9-10
Active: Jul 10
Minor storm: 0
Major storm: 0
Severe storm: 0

Next week, we do not expect any storming event. Currently we expect
quiet to unsettled conditions. The most unsettled episode is
expected at the end of current forecast period, August 9-10.

Tomas Bayer RWC Prague Institute of Geophysics of the ASCR, Prague
Department of Geomagnetism Budkov observatory (BDV)"

Look at all the sunspots on August 3! https://bit.ly/45fC1lE

CMEs: https://bit.ly/3ORBO2J https://bit.ly/3qg2aSe

In an exchange with Carl Luetzelschwab, K9LA and OK1HH, Carl
commented, "Many papers show that climate change has affected the
ionosphere. Is the change enough to actually notice it in
predictions and in on-the-air operations? To answer the prediction
aspect, I looked at Millstone Hill (Massachusetts) foE and foF2
ionosonde data at 1700 UTC (around local noon) for October 1998 (V1
smoothed sunspot number = 70) and January 2023 (V2 smoothed sunspot
number = 114, which gives a V1 number of 80). The data is 24 years
apart, and I figured a trend due to climate change might show up if
there was one. I compared the ionosonde data to what VOACAP
predicted for those two months."

His conclusion? No effect.

V1 and V2 refer to the new and old version sunspot numbers,
explained here: https://www.sidc.be/SILSO/newdataset

This relates to the statement in the OK1HH report in http://arrl.org/w1aw-bulletins-archive/ARLP027/2023 last month about
global changes affecting propagation.

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 27 through August 2, 2023 were 154, 148,
147, 139, 197, 160, and 135, with a mean of 154.3 10.7 cm flux was
165.3, 168.2, 178.6, 174.4, 177.1, 174.7, and 172.9, with a mean of
173. Estimated planetary A indices were 7, 6, 9, 9, 6, 9, and 12,
with a mean of 8.3. Middle latitude A index was 7, 5, 8, 18, 8, 9,
and 10, with a mean of 9.3.
NNNN
/EX


--- MBSE BBS v1.0.8.4 (Linux-x86_64)
* Origin: American Radio Relay League (3:633/280.2@fidonet)

SB PROP @ ARL $ARLP031
ARLP031 Propagation de K7RA

ZCZC AP31
QST de W1AW
Propagation Forecast Bulletin 31 ARLP031

From Tad Cook, K7RA

Seattle, WA August 16, 2024
To all radio amateurs

SB PROP ARL ARLP031
ARLP031 Propagation de K7RA

With sunspot numbers and solar flux at times both above 300, recent daily
space weather has been exciting for radio amateurs who watch the sun. We like higher activity because it correlates with a dense ionosphere, bringing with
it better conditions on higher

frequencies.

This extreme activity also comes with greater geomagnetic disturbance, which cause higher absorption of HF signals.


For example, on August 12 the solar flux was 272.4 and sunspot number was
245. Middle latitude A index was 51 and planetary A index was 122, very high values indicating the G4 geomagnetic storm.


Seven new sunspot groups appeared this week, two on August 8, four on August
11 and one on August 14.


On August 9 the daily sunspot number was 382, the highest in two decades.

Average daily sunspot numbers rose from 222.3 to 255, while average daily
solar flux increased from 255.3 to 284.9.


Average daily planetary A index went from 15.7 to 28.6, and average daily middle latitude A index (measured at a single magnetometer in Virginia) from 13.4 to 17.9.


The solar flux outlook for the next few weeks looks promising, with values peaking at 300 in the first week of September.


Predicted values from forecasters Jones and Kiser at the US Air Force are
230, 225 and 220 on August 16-18, 215 on August 19-20, then 210, 205, 200 and 210 on August 21-24, 220 on August 25-26, 235 on August 27-28, 245 on August 29-30, then 240, 245 and 270 on August 31 through September 2, 300 on
September 3-5, 290 on September 6-7, 280 on September 8, and 270 on September 9-11, then 260 on September 12-14, then 250, 240, 230, 210, 200 and 210 on September 15-20, and 220 on September 21-22.


Predicted planetary A index is 10, 18, 30, 25 and 10 on August 16-20, then 5,
5 and 8 on August 21-23, then 5 on August 24 to September 17, then 18 and 12
on September 18-19, and 5 on September

10 until November.

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere
for August 15, 2024 from F. K. Janda, OK1HH.


The current maximum of the "eleven-year" solar cycle is gradually surpassing all expectations and all predictions. Medium-mass flares (M-class) are
observed almost daily and are often intense enough to silence radio signals
at least in the longer part of short waves by increasing the attenuation in
the lower ionosphere. Large solar flares (X-class) are no exception. They usually (shortly) knock out the entire shortwave range.


Many eruptions are accompanied by a particle cloud ejection (CME). If this happens near or west of the central meridian, it is very likely to "hit" the globe and cause a geomagnetic disturbance. In the case of multiple particle clouds flying toward the Earth at the same time, the first one may clear the way for the following ones, causing an extremely strong disturbance. Which is exactly what we saw on August 11-12.


The geomagnetic disturbance reached G4 level, while not only auroras were observed in mid-latitudes during the disturbance, but also a phenomenon known as STEVE (Strong Thermal Emission Velocity Enhancement), until relatively recently confused with auroras. We observe it as a colored tilted ribbon. Thanks to the simultaneous peak of the Perseids meteor shower, we were able
to witness a truly extraordinary spectacle.


The height of the highest critical frequencies of the f0F2 layer, and thus
the MUF, was on average at an eleven-year low of solar activity on August 12. However, with the difference that as the radio wave passed through the ionosphere, a large attenuation was produced, largely due to scattering on inhomogeneities. The improvement in propagation conditions was slow and gradual. A slightly better 13 August was followed by a deterioration on 14 August. Situation was only slightly above average on 15 August. But with that said, we already knew of other CMEs heading towards Earth.


We don't expect a drop in solar activity anytime soon, if only because we
know of other active regions on the far side of the Sun thanks to helioseismological observations. Soon we will be able to observe them on the eastern edge of the solar disk.


W3LPL wrote in an email:

"Ain't this solar maximum great?

Solar Cycle 25 is now much, much stronger than anyone anticipated, and it s slowly growing stronger through at least this weekend.


Today's Wednesday estimated international sunspot number is 281.

It s increasingly likely that we'll have widespread coast-to-coast and worldwide 6 meter F2 propagation during about half of the days between late October and at least early February.


Widespread F2 openings are likely to bring 6 meter CW and SSB to life like we haven't experienced in more than 20 years.


The first sign of enhanced 6 meter F2 will be increasingly frequent TEP from Europe and North America to South America and the South Atlantic islands. TEP may begin very sporadically by late August and become increasingly frequent later in September and especially during October.


Coast-to-coast F2 propagation and propagation crossing the Atlantic to Europe and Africa may begin sporadically during September and October and become frequent and long lasting by early November.


Effective 6 meter antennas can be very small.

3 element Yagis are small, lightweight and very effective. 20 foot antenna height is adequate but sloping terrain or higher antennas perform much
better. Heights higher that 50 feet are not necessary and in many cases
perform poorly.


Are you ready for this once in a lifetime experience?"

I want to remind everyone of this useful web site:
https://prop.kc2g.com [ https://prop.kc2g.com/ ]

Record breaking number of sunspots: https://www.space.com/sunspots-solar-cycle-25 [ https://www.space.com/sunspots-solar-cycle-25 ]

https://tinyurl.com/k9cnbtt8 [ https://tinyurl.com/k9cnbtt8 ]

Sky & Telescope: https://tinyurl.com/musyznst [ https://tinyurl.com/musyznst
]


Massive flare: https://bit.ly/4fPW1Bp [ https://bit.ly/4fPW1Bp ]

Newsweek on aurora: https://tinyurl.com/3wnckehs [
https://tinyurl.com/3wnckehs ]


Cycle 26: https://tinyurl.com/3jdhyekc [ https://tinyurl.com/3jdhyekc ]

Forbes claims quarter century max: https://tinyurl.com/yhm398ph [ https://tinyurl.com/yhm398ph ]


Red Deer, Alberta: https://tinyurl.com/y5a7sv3f [
https://tinyurl.com/y5a7sv3f ]


Great solar image: https://tinyurl.com/yc84azws [
https://tinyurl.com/yc84azws ]


New report from Tamitha Skov: https://youtu.be/yd1gEZoYpsM [ https://youtu.be/yd1gEZoYpsM ]


Send your tips, reports, observations, questions and comments to
k7ra@arrl.net [ mailto: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 www.arrl.org/propagation [ http://www.arrl.org/propagation ] and the ARRL Technical Information Service web page at, www.arrl.org/propagation-of-rf-signals [ http://arrl.org/propagation-of-rf-signals ] .


For an explanation of numbers used in this bulletin, see www.arrl.org/the-sun-the-earth-the-ionosphere [ 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/ [ http://k9la.us/ ] .


Also, check this: https://bit.ly/3Rc8Njt [ https://bit.ly/3Rc8Njt ]

Instructions for starting or ending email subscriptions to ARRL bulletins are at www.arrl.org/bulletins [ http://arrl.org/bulletins ] .


Sunspot numbers for August 8 through 14 2024 were 337, 382, 234, 194, 245,
199, and 194, with a mean of 255. 10.7 cm flux was 336, 305.5, 291.1, 281.5, 272.4, 259.9, and 248.2, with a mean of 284.9. Estimated planetary A indices were 7, 7, 7, 28, 122, 17, and 12, with a mean of 28.6. Middle latitude A
Index was 11, 9, 8, 23, 51, 12, and 11, with a mean of 17.9.

NNNN
/EX

ARRL The National Association for Amateur Radio®
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--- MBSE BBS v1.0.8.4 (Linux-x86_64)
* Origin: American Radio Relay League (3:633/280.2@fidonet)