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Daily bulletin on solar and geomagnetic activity from the SIDC

Emesso: 2021 Jul 21 1231 UTC

SIDC Forecast

Brillamenti solari

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

Geomagnetism

Quiet (A<20 and K<4)

Protoni solari

Quiet

	10cm flux	Ap
21 Jul 2021	088	008
22 Jul 2021	089	004
23 Jul 2021	090	004

Bulletin

Solar activity was at low levels over the past 24 hours with a single C1.0 class flare, peak time 23:27 UTC on July 20th, produced by the same active region behind the south-east limb, which was responsible for the previous C-class flaring. Apart from that there are currently five active regions on the visible disc: Catania sunspot group 17/NOAA 2842 (magnetic type beta), Catania sunspot group 20/NOAA 2845 (magnetic type alpha), Catania sunspot group 22/NOAA 2846 (magnetic type beta), a newly numbered active region Catania sunspot group 20/NOAA 2847 (magnetic type beta), which rotated from the south-east limb on July 20th and an unnumbered by NOAA active region around N20E27, Catania sunspot group 21 (magnetic type alpha), which emerged on the visible solar disc on July 19th. Catania sunspot group 22/NOAA 2846 has shown most activity over the past 24 hours. It is producing only B-class flares, but has launched an eastward CME, which does not appear to have an Earth-directed. The X-ray flare activity is expected to remain at low levels for the next 24 hours with 70% probability for C-class flaring mainly from the active region behind the south-east limb and possibly from NOAA 2846 or NOAA 2847.

No Earth-directed coronal mass ejections (CMEs) were detected in the available coronagraph imagery. The chances for a glancing blow from the flare-driven eastward CME which left the Sun around 16:36 UTC on July 20th are low, but will be re-analysed as more data comes in.

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 remained under the 1000 pfu threshold and is expected to remain so. The 24h electron fluence was at nominal levels and is expected to remain in the next 24 hours.

Over the past 24 hours the solar wind parameters (ACE and DSCOVR) were slightly enhanced due to the high speed stream (HSS) from a small positive polarity coronal hole (CH). The solar wind speed varied between 380 and 540 km/s. The total magnetic field weakly remained varied between 2 to 6 nT, with a weak Bz component in the range of -5.6 to +6 nT. The interplanetary magnetic field was predominantly in the positive sector (directed away from the Sun) with occasional crossings to the negative sector (towards the Sun).

The geomagnetic conditions over the past 24 hours were quiet to unsettled. Quiet to unsettled geomagnetic conditions are expected for the next 24 hours until the influence of the HSS resides.

Today's estimated international sunspot number (ISN): 064, based on 25 stations.

Solar indices for 20 Jul 2021

Wolf number Catania	///
10cm solar flux	087
AK Chambon La Forêt	018
AK Wingst	016
Estimated Ap	015
Estimated international sunspot number	042 - Based on 28 stations

Noticeable events summary

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

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