Viewing archive of Wednesday, 22 September 2021

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2021 Sep 22 1258 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
22 Sep 2021	085	018
23 Sep 2021	089	018
24 Sep 2021	090	018

Bulletin

Over the past 24 hours, the regions reported yesterday have been rotating on the solar disk. One more unnamed region has appeared to the vicinity of the southern regions Catania 46 and 47. A C1.1-class flare has been recorded from region Catania 45/NOAA 2871. A region is about to rotate on the visible disk on the NE quadrant. Over the next 24 hours, C class flares can be expected.

A possible filament eruption in the southern hemisphere at about Sep 05:38UT will be investigated and further information will be reported.

The greater than 10 MeV proton flux was at background levels in the past 24 hours, and is expected to stay at nominal levels in the next 24 hours. The greater than 2 MeV electron flux remained below the 1000 pfu alert threshold, while the 24h electron fluence was at nominal levels over the past 24 hours. Over the next 24 hours they are expected to remain at those levels, possibly starting to increase towards moderate levels by the end of the period.

Over the past 24 hours the solar wind parameters have been slightly enhanced. The solar wind speed increased, reaching 410 km/s. The total magnetic field strength had values between 1 and 7 nT, while its Bz component varied between -9 and 6 nT. The interplanetary magnetic field phi angle has been on the negative sector (directed towards the Sun) until Sep 21 23:00UT, where it switched to the positive sector. Solar wind parameters are expected to be further enhanced in the coming days, from effects of the high speed stream associated with the negative Coronal Hole present on Central Meridian.

Geomagnetic conditions were at quiet to unsettled levels, with two active periods on Sep 22 00:00-03:00UT and 06:00-09:00UT (NOAA Kp and K Dourbes 1-4) over the past 24 hours. Mostly unsettled conditions with possibility of active events can be expected over the next 24 hours.

Today's estimated international sunspot number (ISN): 080, based on 15 stations.

Solar indices for 21 Sep 2021

Wolf number Catania	076
10cm solar flux	085
AK Chambon La Forêt	019
AK Wingst	010
Estimated Ap	010
Estimated international sunspot number	065 - Based on 27 stations

Noticeable events summary

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

All times in UTC

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