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Solar activity forecast for the period December 01 - December 07, 2023

Activity level: low to moderate
X-ray background flux (1.0-8.0 A): in the range C1.0 - C2.2
Radio flux (10.7 cm): a fluctuation in the range 160-190
Events: class C (2-9/day), class M (0-7/period), class X (0-1/period), proton (0/period)
Relative sunspot number (Ri): in the range 100 - 200

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

Geomagnetic activity forecast for the period December 01 - December 07, 2023

Quiet: Dec 6 - 7
Unsettled: Dec 3 - 6
Active: Dec 1 - 3
Minor storm: Dec 1 - 2
Major storm: possible Dec 1
Severe storm: 0

Currently, solar disk shows the same structure as before the last solar 
cycle when the local K-index in Budkov reached the level 7.
After the last CME, we expect the active conditions with minor to major 
strom within the coming two days. Because of central coronal hole, we 
expect unsettled to active events also at the start of new week.
At the end of currently forecasted period, we expect geomagnetic 
activity decrease to quiet to unsettled level.

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

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere December 01 - December 07, 2023

A week ago the telegraph part of the CQ World Wide DX Contest was held.
Prior to that there were several scenarios of possible developments during
the weekend of November 25 - 26, 2023. In the end the less likely scenario
was the one that was developed. This was due to a relatively inconspicuous
C-class solar flare observed on November 22. However, a detailed analysis
of its evolution revealed that it was preceded by a pre-eruption, which was
the first signal that a CME has likely to follow. Further observations from
satellites and radio telescopes confirmed the CME and measured the speed of
the particle cloud. Its rendezvous with Earth was expected on November 24,
which would have been bad enough for the contest. However, the particle
cloud hit the Earth a day later. Therefore shortwave propagation improved
on November 25 (especially in the afternoon UT, during the positive phase
of the disturbance), whereupon an aggravation occurred on the following day.

The maximum of solar cycle 25 is approaching. CMEs, originating from more
energetic solar flares, or from solar plasma filament eruptions, are
hitting the Earth with increasing frequency. For example, at the time of
this writing, another geomagnetic disturbance is expected as another CME
from the eruption observed on November 28 is expected to hit Earth on
December 1-2.

In the meantime, we are observing a rather large coronal hole in the
southeastern solar disk, which will deflate along its southwestern quadrant
over the next week. In particular, we are observing active regions to the
east of it. This neighbourhood will result in further intensification of
the solar wind and variations in geomagnetic field activity over the next
week. Its predictions do exist, but they will not be reliable.

F. K. Janda, A.R.S. OK1HH
http://ok1hh.nagano.cz/
Emails: ok1hh(at)crk.cz, ok1hh(at)rsys.cz
Pmail: OK1HH(at)OK0NAG.#BOH.CZE.EU

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