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Daily bulletin on solar and geomagnetic activity from the SIDC

Випущено: 2023 Apr 19 1231 UTC

SIDC Forecast

Сонячні спалахи

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

Geomagnetism

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

Сонячні протони

Quiet

	10cm flux	Ap
19 Apr 2023	153	018
20 Apr 2023	153	017
21 Apr 2023	153	006

Bulletin

Solar flaring activity remained at low levels in the past 24 hours. The strongest activity was a C4.8 flare, peak time 15:29 UTC on April 18th, produced by NOAA AR 3280 from the west limb. There are eight active regions on the visible solar disc, the largest one remaining NOAA AR 3282, which is now classified as magnetic type beta together with the second largest region, NOAA 3281. Both regions showed only isolated minor flaring activity. Multiple low C-class flares were produced by NOAA AR 3272, which is currently rotating over the west limb. Minor C-class flaring was produced by NOAA AR 3283 (beta) and a region behind the south-east limb. The solar flaring activity is expected to be at low levels over the next 24 hours. Isolated M-class flaring remains possible.

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

Over the past 24 hours the greater than 10 MeV GOES proton flux was at nominal levels and is expected to remain so in the next 24 hours. The greater than 2 MeV electron flux has been below the1000 pfu threshold and is expected to remain so. The 24h electron fluence was at nominal levels and is expected to remain so over the next 24 hours.

Over the past 24 hours the solar wind parameters (ACE and DSCOVR) are indicative of the influence of one of possibly two ICME arrivals, most probably related to the filament eruptions resulting in partial halo CMEs observed in the coronagraph imagery on April 15th. A fast forward shock was registered in the solar wind parameters around 13:20 UTC on April 18th. In the following hours the solar wind velocity reached a maximum of 623 km/s. The interplanetary magnetic field reached a maximum value of 19.6 nT with a minimum Bz of -16.7 nT. The B field was switching orientation between the positive and the negative sector (directed away from and towards the Sun). Another disturbance arrived in the near-Earth solar wind around 08:30 UTC on April 19th. This is possibly a second ICME transient related to the second partial halo CME from April 15th, though the origin of the disturbance remains to be further determined as more data comes in. Elevated solar wind conditions are expected to prevail on April 19th and April 20th with ongoing ICME influence.

The geomagnetic conditions over the past 24 hours were globally quiet to active and locally in Belgium reached minor storm levels between 17:00 and 20:00 UTC on April 18th. Quiet to active geomagnetic conditions are expected over the next 24 hours with probable minor storm periods and a small chance for reaching moderate storm levels.

Today's estimated international sunspot number (ISN): 105, based on 20 stations.

Solar indices for 18 Apr 2023

Wolf number Catania	178
10cm solar flux	153
AK Chambon La Forêt	026
AK Wingst	016
Estimated Ap	016
Estimated international sunspot number	140 - Based on 29 stations

Noticeable events summary

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

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