Viewing archive of Saturday, 18 December 2021

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2021 Dec 18 1250 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Quiet

	10cm flux	Ap
18 Dec 2021	121	005
19 Dec 2021	125	006
20 Dec 2021	132	006

Bulletin

Six regions and one plage are present on the visible solar disk, of which Catania 84/NOAA 2907, Catania 86/NOAA2908 and Catania 88/NOAA 2911 (configuration beta-gamma) produced C class flares while the last flare in X-ray output originated from Catania 87/NOAA 2909 (configuration beta- gamma) produced a c2.3-class flare on Dec 17 13:25UT. A new region is about to rotate to the visible disk on the southern hemisphere. C-class flares can be expected and M-class flares possible over the next 24 hours.

No Earth directed CMEs were observed in the past 24 hours.

The greater than 10 MeV proton flux was at nominal levels in the past 24 hours and is expected to remain at nominal levels in the next 24 hours. The greater than 2 MeV electron flux remained below the 1000 pfu alert threshold and is expected to remain under the threshold during the next 24 hours. The greater than 2 MeV electron fluence was at nominal levels in the past 24 hours where it is expected to remain.

Over the past 24 hours, the total magnetic field had values between 1 and 5nT, and its southward component, Bz, fluctuated between -4 nT and +4 nT. The solar wind speed ranged from 325 to 390 km/s. The interplanetary magnetic field phi angle was predominantly on the negative sector (directed towards the Sun) until Dec 18 05:30UT, when it was varied. A negative polarity equatorial Coronal Hole(CH) is currently at central meridian. Any possible High Speed Stream (HSS) effects could be expected about Dec 22. A negative polarity CH appeared at the SW quadrant. Any effect of a HSS could be expected about Dec 19-20. Over the next 24 hours, the solar wind paramentes are expected to remain in these levels.

Geomagnetic conditions were quiet over the past 24 hours (NOAA Kp and K-BEL 0-2). Geomagnetic conditions are expected to be quiet to unsettled over the next 24 hours.

Today's estimated international sunspot number (ISN): 099, based on 08 stations.

Solar indices for 17 Dec 2021

Wolf number Catania	134
10cm solar flux	121
AK Chambon La Forêt	005
AK Wingst	003
Estimated Ap	002
Estimated international sunspot number	105 - Based on 14 stations

Noticeable events summary

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

All times in UTC

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