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Daily bulletin on solar and geomagnetic activity from the SIDC

Emesso: 2023 Jul 21 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
21 Jul 2023	180	010
22 Jul 2023	176	018
23 Jul 2023	172	013

Solar Active Regions and flaring

Solar flaring activity over the past 24 hours was at low levels. The largest flare was a C9.7-flare, with peak time 19:49 UTC on July 20, produced by NOAA AR 3373. There are currently 7 numbered active regions on the visible disk. Of the five biggest active regions on disk NOAA AR 3373 is the most magnetically complex. NOAA AR 3372 and NOAA AR 3376 are magnetically decaying and NOAA AR 3377 and NOAA AR 3379 are stable. NOAA AR 3379 has decayed into a plage region. The remaining active regions were quiet and stable. The solar flaring activity is likely to remain at low levels over the coming days with C-class flares expected, M-class flares possible and a low chance for isolated X-class flaring.

Espulsioni di massa coronale

A Coronal Mass Ejection (CME) was observed in LASCO/C2 coronagraph data from 23:24 UTC on July 20 UTC to the south. The CME is associated with a filament eruption of the southern pole and is not expected to arrive at Earth. No other Earth directed CMEs have been detected.

Fori coronali

A negative polarity high latitude coronal hole started to pass the central meridian on July 20.

Vento solare

Over the past 24 hours the solar wind parameters (ACE and DSCOVR) registered signatures of a ICME arrival. A fast forward shock was observed in the solar wind parameters at 16:05 UTC on July 20th. The solar wind velocity increased from 366 km/s to 450 km/s. The interplanetary magnetic field jumped from 5 nT to 12 nT. The Bz reached a minimum of -10 nT. The solar wind density jumped from 2.6 ppc to 11 ppc and reached almost 18 ppc over the next hours. This may mark the expected arrival from the partial halo CME from July 17. The current solar wind speed is close to 400 km/s with magnetic field values around 5 nT. The orientation of the interplanetary magnetic field has mainly stayed in the negative sector (directed towards the Sun). Enhanced solar wind conditions are expected on July 21 and 22, from the expected ICME arrival and possibly weak High Speed Stream (HSS) effects.

Geomagnetism

The geomagnetic conditions over the past 24 hours were quiet to active globally (NOAA KP = 4) with an active period between 15:00 and 21:00 UTC on July 20 and an isolated minor storm period occurred locally (K-Bel = 5) at 19:00 UTC on July 20 associated with the ICME arrival. Unsettled to active conditions are expected with possible minor storm intervals over the next two days.

Proton flux levels

The greater than 10 MeV proton flux was enhanced but remained under the 10pfu threshold and has been gradually decreasing over the last 24 hours. The proton flux is expected to continue to decrease and remain below the threshold in the next 24 hours.

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux measured by GOES-16 and GOES-18 crossed the 1000 pfu alert threshold between 16:35 UTC and 21:50 UTC on July 20 but returned to background levels and is not expected to cross the threshold again in the next 24 hours. The 24h electron fluence was at nominal to moderate levels and is expected to decrease to nominal levels in the next 24 hours.

Today's estimated international sunspot number (ISN): 135, based on 17 stations.

Solar indices for 20 Jul 2023

Wolf number Catania	194
10cm solar flux	184
AK Chambon La Forêt	022
AK Wingst	014
Estimated Ap	013
Estimated international sunspot number	170 - Based on 25 stations

Noticeable events summary

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

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