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Bulletin quotidien sur l'activité solaire et géomagnétique du SIDC

Publié: 2025 Apr 21 1231 UTC

Prévisions SIDC

Éruptions solaires

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

Géomagnétisme

Minor storm expected (A>=30 or K=5)

Moniteur de Flux de Proton

Quiet

	Flux de 10 cm	Ap
21 Apr 2025	156	040
22 Apr 2025	156	026
23 Apr 2025	156	011

Régions solaires actives et éruptions solaires

A total of 7 numbered sunspot groups were identified on the disk over the past 24 hours. SIDC Sunspot Group 473 (NOAA Active Region 4062) currently located at S03W04 is the most complex one, with a Beta-Gamma magnetic configuration, it was stable over the past 24 hours. The largest flare was a C4.3 flare (SIDC Flare 4161) peaking on April 20 at 17:18 UTC, which was produced by SIDC Sunspot Group 475 (NOAA Active Region 4063). Solar flaring activity is expected to be low over the next 24 hours, with C-class flares very likely and a chance for M-class flares.

Éjection de masse coronale

A CME was seen first at 21:48 UTC on April 20 by LASCO C2. It originated from a filament eruption close to the NW limb, with angular width around 70 degrees, it is not expected to arrive to the Earth. No Earth-directed CMEs were observed in the available coronagraph imagery in the last 24 hours.

Trous coronaux

There is a large positive polarity coronal hole (SIDC Coronal Hole 104) covering a large area of the southern hemisphere.This is a recurrent coronal hole, in the previous rotation it had a more developed equatorial extension.

Vent solaire

The Earth is under the influence of a high speed solar wind stream from the large positive polarity coronal hole in the southern hemisphere (SIDC Coronal Hole 104). The solar wind speed has reached 650 km/s (measured by ACE) and is still increasing, the interplanetary magnetic field has reached 19 nT (currently around 12 nT) with Bz down to -13 nT (currently positive).During the previous solar rotation, this same coronal hole produced solar wind speeds approaching 900 km/s at Earth. However, this time the coronal hole's equatorial extension is less developed, which may result in slightly lower wind speeds. Nonetheless, the solar wind speed is expected to be high in the next 24 hours.

Géomagnétisme

Geomagnetic conditions have reached active levels both locally and planetary (K_Bel and Kp up to 4). Due to the effect of the high speed solar wind stream, minor storm levels can be expected (K up to 5), with moderate storms possible (K up to 6).

Niveaux de flux de protons

The greater than 10 MeV proton flux was below the threshold level over the past 24 hours. It is expected to remain below the threshold level over the next 24 hours.

Flux d'électrons sur l'orbite géostationnaire

The greater than 2 MeV electron flux measured by GOES 18 was reaching threshold values between 21:00 UTC and 22:00 UTC on April 20. The greater than 2 MeV electron flux measured by GOES 19 was below the threshold over the past 24 hours. The greater than 2 MeV electron flux is expected to remain below the threshold over the next 24 hours. The 24-hour electron fluence is presently at normal levels and is expected to remain so over the next 24 hours.

Estimation du nombre international de taches solaires (ISN) pour aujourd'hui : 131, sur la base de 11 stations.

Indices solaires pour 20 Apr 2025

Nombre de Wolf, observé par Catania	///
Flux solaire à 10 cm	156
AK Chambon La Forêt	021
AK Wingst	014
Ap estimé	014
Nombre international de taches solaires estimé	125 - Basé sur 18 stations

Résumé des événements marquants

Données fournies par le Solar Influences Data analysis Center© - SIDC - Traité par SpaceWeatherLive

Toutes les heures sont indiquées en UTC

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