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Daily bulletin on solar and geomagnetic activity from the SIDC

Emesso: 2021 Apr 15 1237 UTC

SIDC Forecast

Brillamenti solari

Quiet conditions (<50% probability of C-class flares)

Geomagnetism

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

Protoni solari

Quiet

	10cm flux	Ap
15 Apr 2021	076	015
16 Apr 2021	076	015
17 Apr 2021	074	024

Bulletin

Solar activity remained at very low levels over the last 24 hours. Sunspot group Catania 86 (NOAA 2814) increased in area and grew its number of visible spots. It registered low levels of activity and remained magnetic type Beta. A faint new sunspot group is developing around S22E02 and another active region is currently rotating from the south-east limb. The flaring activity within the next 24 hours is expected to remain low with a minor chance for a C-class flare.

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 remained under the 1000 pfu threshold and is expected to remain so. The 24h electron fluence was at nominal levels and is expected to be predominantly at nominal in the next 24 hours.

Over the past 24 hours the solar wind parameters (ACE and DSCOVR) registered the arrival of an ICME with associated increase in the solar wind density and decrease in temperature. The total magnetic field reached a magnitude of 10.5 nT with a minimum Bz of -7 nT. The ICME is most probably related to a slow CME which left off the west solar limb in the UTC morning of April 10th. Since the CME was rather slow (with estimated speed below 350 km/s) it did not cause a prominent increase in the solar wind speed. The arrival of the ICME caused an isolated period of globally active geomagnetic conditions between 21:00 UTC on April 14th and 00:00 UTC on April 15th and later on a minor geomagnetic storm between 06:00 UTC and 09:00 UTC on April 15th. Locally the geomagnetic conditions reached only active levels with K Dourbes = 4 between 23:00 UTC on April 14th and 02:00 UTC on April 15th.

Quiet to active geomagnetic conditions are expected in the next 24 hours with the arrival of a CIR. On April 16th we expect the arrival of a HSS associated with a small equatorial negative polarity coronal hole (CH) crossed the central meridian on April 13th. Unsettled to active geomagnetic conditions are expected for that day with a change for a minor geomagnetic storm. On April 17th the arrival of a high-latitude extension of the negative polarity southern polar coronal hole might result in more minor geomagnetic storms.

Today's estimated international sunspot number (ISN): 023, based on 17 stations.

Solar indices for 14 Apr 2021

Wolf number Catania	021
10cm solar flux	074
AK Chambon La Forêt	020
AK Wingst	008
Estimated Ap	008
Estimated international sunspot number	020 - Based on 29 stations

Noticeable events summary

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

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