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Daily bulletin on solar and geomagnetic activity from the SIDC

Emesso: 2021 Dec 24 1309 UTC

SIDC Forecast

Brillamenti solari

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

Geomagnetism

Quiet (A<20 and K<4)

Protoni solari

Quiet

	10cm flux	Ap
24 Dec 2021	128	004
25 Dec 2021	126	005
26 Dec 2021	123	004

Bulletin

Solar activity was at low levels over the past 24 hours with over twenty C-class flares. There remained nine numbered active regions on the visible disc with NOAA 2907 (beta-gamma) being the largest one with the most complex magnetic field configuration. It increased its area and number of sunspots and produced C-class flares, the strongest one being C5.5-class with peak time at 07:19 UTC on Dec 24th. The remaining C-class flaring activity was produced by the neighbouring region NOAA 2908 (beta), which decreased in magnetic complexity and significantly reduced its number of sunspots, and active region NOAA 2017 (beta), which did not change its magnetic type, but substantially increased its number of sunspots. The strongest flare over the last 24 hours was a C7.4-class with peak time 03:42 UTC on Dec 24th produced by NOAA 2017, followed by a C5.7-class with peak time 06:27 UTC on Dec 24th produced by NOAA 2908. The remaining of the active regions on the visible solar disk remained mostly stable and did not show significant flaring activity. The X-ray flare activity is expected to be predominantly at low levels for the next 24 hours with a 40% chance for isolated 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 periodically exceed the 1000 pfu threshold over the next 24 hours. The 24h electron fluence was at 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 diminishing influence of the high-speed stream (HSS). The solar wind velocity continued to gradually decline and the speed has decreased from about 550 km/s towards 415 km/s. The interplanetary magnetic field was at background levels with values between 2.1 nT and 5 nT. The Bz-component varied between -3.4 and 4.6 nT. The polarity of the magnetic field remained predominantly in the negative sector reflecting the polarity of the geo- effective colonial hole with a clear rotation around 06 UTC this morning, which might be an indication of the magnetic cloud from the expected CME flank. The solar wind parameters are expected to continue their decline towards background solar wind conditions. Any remaining passage of the CME from Dec 20th are not expected to cause large disturbances. A midlatitude extension of the norther positive polarity coronal hole has crossed the central meridian and the related HSS is expected to influence the Earth from Dec 27th onwards.

The geomagnetic conditions over the past 24 hours were quiet. Mostly quiet geomagnetic conditions are expected for the next 24 hours with possible isolated unsettled periods. Quiet conditions to prevail until Dec 27th when unsettled to active conditions with isolated minor storms can be expected.

Today's estimated international sunspot number (ISN): 113, based on 04 stations.

Solar indices for 23 Dec 2021

Wolf number Catania	///
10cm solar flux	130
AK Chambon La Forêt	007
AK Wingst	004
Estimated Ap	003
Estimated international sunspot number	141 - Based on 12 stations

Noticeable events summary

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

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