Viewing archive of Tuesday, 20 July 2021

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2021 Jul 20 1236 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Quiet

	10cm flux	Ap
20 Jul 2021	086	013
21 Jul 2021	085	006
22 Jul 2021	084	004

Bulletin

Solar activity was at low levels over the past 24 hours with 2 C-class flares, namely C1.3 flare with peak time 19:07 UTC on July 19th and C1.2-class flare with a peak time at 20:52 UTC, produced by an active region behind the south-east limb. There are three active regions on the visible disc: Catania sunspot group 17/NOAA 2842 (magnetic type beta), Catania sunspot group 20/NOAA 2845 (magnetic type alpha) and the newly numbered region close to the south-east limb, Catania sunspot group 22/NOAA 2846 (magnetic type beta). Active region NOAA 2844 has now decayed into page. Catania sunspot group 17/NOAA 2842 has now increased in area and doubled its number of sunspots, remaining the most complex region on the visible disc. The X-ray flare activity is expected to remain at low levels for the next 24 hours with 50% probability for C-class flaring mainly from the active region behind the south-east limb and possibly from NOAA 2842 as well.

No Earth-directed coronal mass ejections (CMEs) were detected in the available coronagraph imagery.

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) reflect the crossing of a solar sector boundary, possibly related to the small equatorial coronal hole (CH) which crossed the central meridian on July 17th. The solar wind speed increased from 377 to 510 km/s. The total magnetic field varied between 2.3 and 7.6 nT with a Bz component in the range of -6.5 to +5.5 nT. The interplanetary magnetic field was predominantly in the positive sector (directed away from the Sun), most probably reflecting the polarity of the small geo-effective equatorial CH.

The geomagnetic conditions over the past 24 hours were quiet to unsettled. Quiet to unsettled geomagnetic conditions are expected for the next 24 hours while the influence of the high speed stream from the equatorial CH persists.

Today's estimated international sunspot number (ISN): 042, based on 24 stations.

Solar indices for 19 Jul 2021

Wolf number Catania	062
10cm solar flux	083
AK Chambon La Forêt	018
AK Wingst	012
Estimated Ap	011
Estimated international sunspot number	044 - 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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