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Daily bulletin on solar and geomagnetic activity from the SIDC

Emesso: 2021 Sep 08 1231 UTC

SIDC Forecast

Brillamenti solari

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

Geomagnetism

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

Protoni solari

Quiet

	10cm flux	Ap
08 Sep 2021	102	021
09 Sep 2021	100	029
10 Sep 2021	098	018

Bulletin

Solar activity was at low levels with three C-class flares over the past 24 hours. Active region NOAA 2863 has remained stable and decreased its magnetic complexity to type alpha. NOAA 2866 (beta) remains the largest active region with highest number of spots. Nevertheless it produced only a single C1.2-class flare (peak time 10:26 UTC on Sept 8th). The neighbouring region NOAA 2868 (beta) produced a C1.1-class flare (peak time 03:14 UTC on Sept 8th). NOAA 2864 produced a longer duration C2.3-class flare (peak time 00:09 UTC on Sept 8th), accompanied by a filament eruption. A new bi-polar region has emerged around S36E20 (NOAA 2869/Catania sunspot group 41) and its evolution will be further monitored. The X-ray flare activity is expected to be at low levels for the next 24 hours with 75% probability for C-class flaring and a minor chance for an M-class flare.

No Earth-directed CMEs were observed in the available coronagraph imagery over the past 24 hours. A westward CME has left the Sun during the night of Sept 7th following the C2.3-class flare from NOAA 2864 accompanied by a filament eruption and a clear coronal dimming. This ejecta will be further analysed as more coronagraph data becomes available.

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 predominantly below the 1000 pfu threshold with a very short crossing between 17:30 and 18:15 UTC on Sept 07th. The 2MeV electron flux is expected to remain below the 1000 pfu threshold. The 24h 2MeV electron fluence was at nominal levels and is expected to remain so in the next 24 hours.

Over the past 24 hours the solar wind parameters (ACE and DSCOVR) registered the arrival of a high speed stream (HSS), most probably attributed to the negative polarity coronal hole residing on the central meridian on Sept 1st and Sept 2nd. The solar wind speed increased from 294 to 440 km/s. The total magnetic field was enhanced reaching up to 12 nT. The Bz component reached -9 nT. The interplanetary magnetic field was fluctuating between the positive and the negative sector.

The geomagnetic conditions over the past 24 hours were globally quiet to active, while locally minor storm conditions were registered in the short period between 00:00 and 02:00 UTC on Sept 8th. Predominantly unsettled to active geomagnetic conditions are expected for the next 24 hours with possible intervals with minor geomagnetic storms. There is a minor chance for a major storm on Sept 09th or Sept 10th should any of the predicted CMEs reach the Earth or should a HSS related to the extension of the southern polar coronal hole, which crossed the central meridian on Sept 6th, arrive to the Earth.

Today's estimated international sunspot number (ISN): 095, based on 21 stations.

Solar indices for 07 Sep 2021

Wolf number Catania	///
10cm solar flux	101
AK Chambon La Forêt	028
AK Wingst	013
Estimated Ap	013
Estimated international sunspot number	082 - Based on 27 stations

Noticeable events summary

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

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