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Daily bulletin on solar and geomagnetic activity from the SIDC

Emesso: 2025 Aug 13 1239 UTC

SIDC Forecast

Brillamenti solari

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

Geomagnetism

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

Protoni solari

Warning condition (activity levels expected to increase, but no numeric forecast given)

	10cm flux	Ap
13 Aug 2025	152	013
14 Aug 2025	152	015
15 Aug 2025	152	007

Solar Active Regions and flaring

Solar flaring activity was low over the past 24 hours, with only C-class flares identified. A total of 10 numbered sunspot groups were observed on the solar disk. The most complex regions include SIDC Sunspot Group 590 (NOAA Active Region 4172), located at N09W36, with a Beta-Gamma magnetic configuration that was decreasing, and SIDC Sunspot Group 596 (NOAA Active Region 4178), located at N10W64, which has a Beta magnetic configuration and was also decreasing. The most productive region was SIDC Sunspot Group 590, which produced the largest flare, a C8.3 flare (SIDC Flare 5133) peaking on August 12 at 18:43 UTC. Other regions showed limited activity: SIDC Sunspot Groups 598 (NOAA Active Region 4180) was growing, while SIDC Sunspot Groups 554, 558, 522, 597, 600, and 601 remained stable. Solar flaring activity is expected to remain low over the next 24 hours, with C-class flares very likely and a chance for M-class flares.

Espulsioni di massa coronale

No Earth-directed CMEs were observed over the past 24 hours. Large filaments are currently present on the disk facing Earth; however, they remain stable, and no eruptions have been detected.

Fori coronali

Three coronal holes are currently present on the solar disk. A small coronal hole, SIDC Coronal Hole 125, is located on the western side of the Sun. The elongated, southern, positive-polarity SIDC Coronal Hole 123 continues to cross the central meridian since August 6. Additionally, SIDC Coronal Hole 116, a mid-latitude coronal hole with negative polarity, has returned and is now positioned on the eastern side of the Sun.

Vento solare

Over the past 24 hours, solar wind conditions were influenced by high-speed streams associated with the positive-polarity SIDC Coronal Hole 123. Solar wind speed varied between 600 km/s and 700 km/s and is currently decreasing to approximately 500 km/s. The total interplanetary magnetic field (Bt) fluctuated between 5 nT and 7.3 nT, with the Bz component ranging from -6.0 nT to 6.3 nT. Due to the large extent of SIDC Coronal Hole 123, which continues to cross the central meridian, its influence on solar wind conditions is expected to persist over the next few days.

Geomagnetism

Geomagnetic conditions have been mainly unsettled over the past 24 hours. NOAA Kp indices ranged from 2 (quiet) to 3 (unsettled), while the Belgian K-index showed mainly unsettled conditions with a short period of active condition, ranging from 2 (quiet) to 3 (unsettled), with brief episodes reaching 4 (active). Unsettled geomagnetic conditions are expected to continue, with possible short intervals of active conditions.

Proton flux levels

Proton flux remained quiet over the past 24 hours, with values below the 10 pfu threshold. However, due to the number of sunspot groups on the disk and, in particular, the recent activity from SIDC Sunspot Group 592 (NOAA Active Region 4173) and SIDC Sunspot Group 588 (NOAA Active Region 4168), both of which have rotated over the west limb but remain magnetically connected to the Sun-Earth line, a potential enhancement of the proton flux cannot be fully excluded.

Electron fluxes at geostationary orbit

The >2 MeV electron flux measured by GOES 18 and GOES 19 exceeded the 1000 pfu threshold in response to high-speed streams associated with SIDC Coronal Hole 123. Electron flux levels are expected to fluctuate around the 1000 pfu threshold over the next 24 hours. The 24-hour electron fluence remains at moderate levels and is expected to stay at these levels over the next 24 hours.

Today's estimated international sunspot number (ISN): 184, based on 24 stations.

Solar indices for 12 Aug 2025

Wolf number Catania	///
10cm solar flux	152
AK Chambon La Forêt	020
AK Wingst	017
Estimated Ap	018
Estimated international sunspot number	170 - Based on 28 stations

Noticeable events summary

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

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