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Daily bulletin on solar and geomagnetic activity from the SIDC

Emesso: 2021 Dec 23 1253 UTC

SIDC Forecast

Brillamenti solari

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

Geomagnetism

Active conditions expected (A>=20 or K=4)

Protoni solari

Quiet

	10cm flux	Ap
23 Dec 2021	140	006
24 Dec 2021	140	016
25 Dec 2021	135	009

Bulletin

Solar activity was at low levels over the past 24 hours with fourteen C-class flares. There were nine numbered active regions on the visible disc, the most prominent of which remained NOAA 2907 (beta-gamma). It was also responsible for twelve our of the fourteen detected C-class flares, the strongest one being C8.8-class with peak time at 18:08 UTC on Dec 22nd. NOAA 2908 has increased its complexity and is now classified as magnetic type beta-gamma. Nevertheless it remained mostly stable and produced only a single C-class flare. A new active region NOAA 2918 (beta) situated north-eastward from NOAA 2915 (beta) was recently numbered and produced a low C-class as well. The other active regions have shown very low levels of activity. NOAA 2916 has increased the complexity of its underlying magnetic field configuration and is now classified as magnetic type beta. Another new active region with beta-type magnetic configuration was numbered as NOAA 2917. NOAA 2910 has rotated behind the west limb, while NOAA 2914 (previously beta) and NOAA 2913 (previously alpha) have decayed into plages. The X-ray flare activity is expected to be predominantly at low levels for the next 24 hours with a 45% chance for isolated M-class flaring and 5% chance for an X-class flare.

Currently no Earth-directed coronal mass ejections (CMEs) were detected in the available coronagraph imagery. The eruption following the C4.9-class flare peaking at 19:23 UTC on Dec 21st seems to be rather faint and is not expected to have significant impact on Earth.

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 has exceeded the 1000 pfu threshold and is expected to periodically exceed the 1000 pfu threshold over the next 24 hours. The 24h electron fluence reached moderate levels and is expected to remain at moderate levels over the next 24 hours.

Over the past 24 hours all solar wind parameters (ACE and DSCOVR) remained under the influence of a high-speed stream (HSS). The solar wind velocity started a gradual decrease from 580 km/s towards 510 km/s. The interplanetary magnetic field was at background levels with values between 2.8 nT and 5.6 nT. The Bz-component varied between -3.8 and 3.8 nT. The polarity of the magnetic field remained predominantly in the negative sector reflecting the polarity of the geo-effective colonial hole. The solar wind parameters are expected to remain enhanced as they slowly return towards background solar wind conditions. Small fraction of the CME, which left the Sun on Dec 20th, could arrive early tomorrow and further perturb the solar wind conditions, resulting in stronger magnetic field and enhanced density.

The geomagnetic conditions over the past 24 hours were quiet to unsettled. Quiet to active geomagnetic conditions are expected for the next 24 hours due to the expected CME arrival. Isolated minor storms are unlikely, but remain possible, depending on the induced magnetic field perturbations.

Today's estimated international sunspot number (ISN): 142, based on 07 stations.

Solar indices for 22 Dec 2021

Wolf number Catania	///
10cm solar flux	140
AK Chambon La Forêt	017
AK Wingst	013
Estimated Ap	011
Estimated international sunspot number	147 - Based on 18 stations

Noticeable events summary

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

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