Viewing archive of Tuesday, 21 September 2021

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2021 Sep 21 1443 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Quiet

	10cm flux	Ap
21 Sep 2021	080	008
22 Sep 2021	083	006
23 Sep 2021	086	016

Bulletin

Five regions are present on the Sun, NOAA 2871, 2872, 2873 as well as two small, bipolar, unnamed regions in the southern hemisphere. Over the past 24 hours, two C-class flares have been recorded, the strongest one being a C1.8-class flare. The flares have been reported to originate from region NOAA 2073 and NOAA 2871. Two unnumbered regions, of beta configuration are in North and NE Over the next 24 hours, C class flares can be expected, especially from region NOAA 2871.

No Earth directed Coronal Mass Ejections (CMEs) were observed in the available coronagraphic imagery.

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.

Over the past 24 hours the solar wind speed varied between 300 to 345 km/s. The total magnetic field strength had values between 3 and 7 nT, while its Bz component varied between -4 and 4 nT. The interplanetary magnetic field phi angle has been on the negative sector (directed towards the Sun). The effects of the high speed stream associated with the negative Coronal Hole present on Central Meridian can be expected at about Sep 23-24. Over the next 24 hours, solar wind conditions continue at about those levels, possibly slightly enhanced.

Geomagnetic conditions were at quiet to unsettled levels (NOAA Kp 0-3 and K Dourbes 0-2) over the past 24 hours. Quiet to unsettled conditions are expected over the next 24 hours.

Today's estimated international sunspot number (ISN): 065, based on 21 stations.

Solar indices for 20 Sep 2021

Wolf number Catania	044
10cm solar flux	080
AK Chambon La Forêt	008
AK Wingst	004
Estimated Ap	003
Estimated international sunspot number	043 - Based on 22 stations

Noticeable events summary

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

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