Viewing archive of Friday, 10 September 2021

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2021 Sep 10 1234 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

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

Solar protons

Quiet

	10cm flux	Ap
10 Sep 2021	100	017
11 Sep 2021	096	006
12 Sep 2021	096	008

Bulletin

Over the past 24 hours the solar activity has decreased to very low levels. There remain to be six active regions present on the visible solar disc. NOAA 2866/Catania 40 (beta) remained the largest active region and almost doubled its number of sunspots, yet it produced only high B-class flaring. NOAA 2868/Catania 39 (beta-gamma) has increased its magnetic complexity and produced a long-duration high B-class flaring. NOAA 2864/Catania 38 (alpha) and NOAA 2863/Catania 37 (alpha) remained stable and are now approaching the west limb. NOAA 2869/Catania 41 (beta) showed slight development, but no sign of activity yet. The recently rotated from the south-east limb active region Catania 42 has now been numbered as NOAA 2870 and remained a simple alpha. The X-ray flare activity is expected to be at very low to low levels for the next 24 hours with remaining significant change for C-class flaring and a minor chance for M-class flaring from NOAA 2866 or NOAA 2868.

No Earth-directed CMEs were detected in the available coronagraph imagery over the past 24 hours. An update to yesterday’s forecast: a minor glancing blow from the CME lunched from the Sun around 00:36 UTC on Sept 8th is now estimated to arrive to the Earth during early on Sept 12th.

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 below the 1000 pfu threshold and is expected to remain so in the next 24 hours. The 24h fluence for the greater than 2MeV electron flux was at nominal levels and is expected to remain so in the next 24 hours.

Around 09:45 UTC this morning the solar wind parameters (ACE and DSCOVR) registered the arrival of an ICME (potentially the partial halo CME launched from the Sun on Sept 06th from NOA 2865 and forecasted to arrive today). The solar wind speed is still low, below 400 km/s, but is expected to increase in the upcoming hours. The total magnetic field is currently at 11 nT and could show further increase. Since the arrival of the ICME the Bz component has remained positive with a maximal value of 6.8 nT. The interplanetary magnetic field showed a smooth rotation from the negative to the positive sector registering the arrival of the ICME.

The geomagnetic conditions over the past 24 hours were quiet to unsettled. Quiet to active geomagnetic conditions are expected for the next 24 hours with a small chance of a minor storm later today.

Today's estimated international sunspot number (ISN): 089, based on 09 stations.

Solar indices for 09 Sep 2021

Wolf number Catania	116
10cm solar flux	100
AK Chambon La Forêt	008
AK Wingst	006
Estimated Ap	004
Estimated international sunspot number	096 - Based on 25 stations

Noticeable events summary

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

All times in UTC

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