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Daily bulletin on solar and geomagnetic activity from the SIDC

Vydáno: 2021 Nov 01 1244 UTC

SIDC Forecast

Sluneční erupce

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

Geomagnetism

Quiet (A<20 and K<4)

Sluneční protony

Warning condition (activity levels expected to increase, but no numeric forecast given)

	10cm flux	Ap
01 Nov 2021	100	008
02 Nov 2021	098	007
03 Nov 2021	095	007

Bulletin

Solar activity was dominated by an M1.5 flare from NOAA active region 2887 peaking at 1:45UT. NOAA active region 2887 seems to be in decay overall and to simplify in complexity but remains a likely source for C flares and possibly M flares with only a minor chance for an X flare. Meanwhile NOAA active regions 2892 and 2889 have lost their spots, while NOAA active region 2891 remains a beta region with a significant likelihood of producing C class flaring. Overall C flares are very likely to occur with also M class flares still possible.

The M1.5 flare was associated with an EUV dimming and wave, as well as type II and IV radio bursts. An associated partial halo CME is visible in LASCO C2 coronagraph images from 2:00UT onwards. The CME is mainly directed towards the South-West, with an angular width of around 230 degrees. Its speed is measured to be around 900 km/s and an arrival of the CME at Earth is expected around 2UT November 4.

The C2.9 flare from NOAA active region 2891 peaking at 7:06UT October 31 seems to be associated with a Eastbound CME first visible in LASCO C2 coronagraph images at 8:24 UT on October 31. The CME appears slow (of the order of the background Solar wind) and if a possible Earth directed component would arrive it is likely to pass unnoticed, especially in combination with the higher probability and more significant influence expected from the November 1 CME.

The more than 10MeV proton flux remained slightly enhanced but below the event threshold. An increase, possibly related to the 2UT CME could be noticed. Given the increased values and the possibility of significant activity from NOAA region 2887, there is some possibility of a proton event in the next 24-48 hours. The greater than 2 MeV electron flux was below the 1000 pfu threshold. The 24h electron fluence is at low to nominal levels and expected to remain so.

Solar wind conditions showed the passage of the CME of October 28, with less impact than anticipated. Solar wind speed was mostly in the 400-450 km/s at the start of the period, and has decreased to slow Solar wind values this morning to currently around 350 km/s. The magnitude of the interplanetary field remained elevated initially, but decreased below 10 nT in the first hour of the period and then followed an overall decreasing trend to below 5nT currently. The Bz component of the magnetic field was strongly negative, below -10nT until just before the start of the period but was insignificant since noon October 31. The orientation of the magnetic field indicated connection to a positive polarity sector, throughout the period. Quiet Solar wind conditions are expected in the following 24-48 hours, then followed by an expected arrival of the CME of November 1 in the morning of November 4.

Geomagnetic conditions showed, at the start of the period a brief episode of minor geomagnetic storm conditions (NOAA Kp reaching 5, while locally only active conditions were measured), and then decreased gradually to quiet to unsettled conditions by the end of the period. Quiet conditions are expected over the next 24-48 hours, with afterwards, from November 4, minor geomagnetic storming possible, associated to the arrival of the CME of November 1.

Today's estimated international sunspot number (ISN): 050, based on 11 stations.

Solar indices for 31 Oct 2021

Wolf number Catania	///
10cm solar flux	103
AK Chambon La Forêt	028
AK Wingst	017
Estimated Ap	018
Estimated international sunspot number	068 - Based on 25 stations

Noticeable events summary

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

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