Predikce sluneční a geomagnetické aktivity

Solar activity forecast for the period

April 19 - April 25, 2024

Activity level:	mostly low to moderate
X-ray background flux (1.0-8.0 A):	in the range B5.2 - C4.5
Radio flux (10.7 cm):	a fluctuation in the range 119-258
Events:	class C (2-8/day), class M (0-8/period), class X (0-1/period), proton (0/period)
Relative sunspot number (Ri):	in the range 80-250

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

Geomagnetic activity forecast for the period

April 19 - April 25, 2024

Quiet:	Apr 20, 22 - 24
Unsettled:	Apr 19, 20 - 22
Active:	possible Apr 21, 25
Minor storm:	possible about Apr 21, 25
Major storm:	0
Severe storm:	0
Geomagnetic activity summary:	Last week, the geomagnetic activity peaked locally at April 16. At Budkov observarory, we recorded double K-index at level 5 (6 pm till 9 pm UTC). Since this event, we expect geomagnetic activity decrease to unsettled level. Next days, we expect geomagnetic activity decrease although it can be interrupted by any active event about Sunday, April 21. Since Monday, April 22, we expect at most quiet to unsettled level. At the end of currently forecasted period, an another active event is possible.

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

Geomagnetic activity forecast for the period

April 19 - April 25, 2024

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 April 19 - April 25, 2024
Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere – April 18, 2024

Over the past weekend, active sunspot regions began to emerge on the eastern limb as expected. Curiosity about what we would actually see was heightened because their flare activity during the last rotation was somewhat higher than usual. Therefore, the CME from a moderate eruption in the northern hemisphere of the Sun on April 11 with a maximum at 1706 UT was not a surprise. The arrival of the particle cloud on April 14 was therefore expected, but it missed the Earth.

Another CME was ejected towards Earth on 12 April. Although neither CME was particularly strong, a G1 class geomagnetic storm was expected. This occurred on 16 April, so either the particle cloud moved more slowly or travelled along a longer path towards the Earth. Either way, the disturbance worsened shortwave propagation conditions on April 16. But their improvement was rapid, starting as early as April 17. The credit for this goes to the increasing solar radiation coming from the active regions we can observe on the Sun this week and next.

Another weak CME left the Sun on April 15, and the Earth's impact was calculated for April 18. However, all predictions of disturbances at the current stage of the 11-year cycle are unreliable. They are usually either late (by a day or so) or not at all. The important thing is the result - due to the relatively high solar activity and at the same time the small number of geomagnetic disturbances, the shootwave prpagation conditions are mostly above average.

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

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

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