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Daily bulletin on solar and geomagnetic activity from the SIDC

Emesso: 2021 Dec 25 1244 UTC

SIDC Forecast

Brillamenti solari

C-class flares expected, (probability >=50%)

Geomagnetism

Quiet (A<20 and K<4)

Protoni solari

Quiet

	10cm flux	Ap
25 Dec 2021	121	006
26 Dec 2021	122	003
27 Dec 2021	122	015

Bulletin

Solar activity was at low levels over the past 24 hours with ten C-class flares. There are eight numbered active regions on the visible disc. The most complex one remaining NOAA 2907 (beta-gamma), which has decreased its level of activity to only three C-class flares and is now approaching the west limb. The strongest flaring activity over the past 24 hours was a C5.2-class flare with peak time 12:12 UTC on Dec 24th produced by NOAA 2908 (beta), which underwent a decay, decreasing its area and trailing spots number. NOAA 2016 (beta) and NOAA 2918 (beta) showed significant grow, increasing their number of trailing spots, and produced low C-class flaring activity. NOAA 2911 has decayed into plage. The X-ray flare activity is expected to be at low levels for the next 24 hours with a 30% chance for M-class flaring.

No Earth-directed coronal mass ejections (CMEs) were detected in the available coronagraph imagery.

The greater than 10 MeV proton flux was at nominal levels in the past 24 hours and is expected to remain so in the next 24 hours. The greater than 2MeV electron flux was oscillating around the 1000 pfu threshold and is expected to sporadically exceed the 1000 pfu threshold over the next 24 hours. The 24h electron fluence was at moderate levels and is expected to be at the border of moderate to nominal levels over the next 24 hours.

Over the past 24 hours all solar wind parameters (ACE and DSCOVR) continued their return to background slow solar wind conditions. The solar wind speed varied in the range of 408 km/s to 500 km/s. The interplanetary magnetic field was at background levels with values between 1.8 nT and 6.2 nT. The Bz-component varied between -5.4 and 3.9 nT. The polarity of the magnetic field remained predominantly in the negative sector until midnight on Dec 24th when another rotation in the magnetic field was detected, potentially reflecting the passage of a magnetic cloud related to the CME from Dec 20th. The solar wind parameters are expected to continue their decline towards background solar wind conditions. An equatorial positive polarity coronal hole has crossed the central meridian and the related high-speed stream (HSS) is expected to influence the Earth from Dec 28th onwards on top of the HSS from the extension of the positive polarity northern polar hole, which is expected to reach the Earth on Dec 27th.

The geomagnetic conditions over the past 24 hours were mostly quiet with isolated unsettled periods caused by the passage of the solar wind structure. Mostly quiet geomagnetic conditions are expected for the next 24 hours with remaining possibility for isolated unsettled periods. Quiet conditions are expected to prevail until the expected arrival of the next HSS on Dec 27th.

Today's estimated international sunspot number (ISN): 126, based on 05 stations.

Solar indices for 24 Dec 2021

Wolf number Catania	///
10cm solar flux	126
AK Chambon La Forêt	012
AK Wingst	006
Estimated Ap	005
Estimated international sunspot number	115 - Based on 10 stations

Noticeable events summary

Provided by the Solar Influences Data analysis Center© - SIDC - Processed by SpaceWeatherLive

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