Predikce sluneční a geomagnetické aktivity

Solar activity forecast for the period

September 22 - September 28, 2023

Activity level:	mostly moderate
X-ray background flux (1.0-8.0 A):	in the range B9.5 - C1.8
Radio flux (10.7 cm):	a fluctuation in the range 145-165
Events:	class C (4-10/day), class M (0-3/day), class X (0-1/period), proton (0/period)
Relative sunspot number (Ri):	in the range 130 - 280

Martina Pavelková
RWC Prague, Astronomical Institute, Solar Dept., Ondrejov, Czech Republic
e-mail: sunwatch(at)asu.cas.cz

Geomagnetic activity forecast for the period

September 22 - September 28, 2023

Quiet:	Sep 24 - 27
Unsettled:	Sep 22 - 24, 27 - 28
Active:	Sep 23, 28
Minor storm:	Sep 28
Major storm:	0
Severe storm:	0
Geomagnetic activity summary:	After the last active episode with minor storm event (at Budkov observatory, the highest local K-index peaked at level 5), we expect geomagnetic activity decrese to unsettled level wduring coming two days. At the start of the new week, since Monday, September 25, we expect at most quiet conditions till the end of currently forecasted interval. At the end of this weekly forecast, another active event with posible storming event is expectable.

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

Geomagnetic activity forecast for the period

September 22 - September 28, 2023

Geomagnetic field will be:

Quiet on:
Quiet to unsettled on:
Quiet to active on:
Unsettled to active on:
Active to disturbed:
Solar wind will intensify on:

Remarks:

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere September 22 - September 28, 2023

Although the site SolarHam.net (https://solarham.net/, launched on March 15, 2006, created and still maintained solely by Kevin VE3EN) is primarily intended for amateur radio users, it is also very well regarded by professional astronomers. In addition to information about the Sun, it contains everything needed to understand the causes of changes in the ionosphere, and also provides an overview and forecast of the Earth's magnetic field activity. On Thursday, September 21, we read: 'Solar activity is predicted to remain at low (C-Flares) to moderate (M-Flares) levels during the next 24 hours. AR 3435 is considered the most likely region to produce a moderate to strong solar flare."

The information can be supplemented by saying that the level of solar activity has been rising in recent days, and this rise was accompanied by an increase in solar wind speed from 400 km/s to over 600 km/s between 18-20 September. In particular, the solar wind proton influx increased significantly on 18 September; moreover, a geomagnetic disturbance with intensity G2 (Moderate) to G3 (Strong) took place on 18-19 September.

The Earth's ionosphere responded to these events with a significant decrease in MUF, especially since 18 September. Shortwave propagation conditions were above average for the last time on 10-12 September, including a positive phase of the disturbance on the latter day. Around the equinox we usually expect improvement, but now it was the opposite as a result of disturbances.

As another very good source of information, I can particularly recommend the Space Weather Monitor (https://www.ionosonde.iap-kborn.de/actuellz.htm), as it also contains the most important data on the Earth's ionosphere.

F. K. Janda, A.R.S. OK1HH

e-mail: ok1hh(at)crk.cz; ok1hh(at)rsys.cz

Pmail: OK1HH(at)OK0NAG.#BOH.CZE.EU