Viewing archive of Sunday, 17 December 2023

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2023 Dec 17 1230 UTC

SIDC Forecast

Solar flares

M-class flares expected (probability >=50%)

Geomagnetism

Minor storm expected (A>=30 or K=5)

Solar protons

Quiet

	10cm flux	Ap
17 Dec 2023	151	023
18 Dec 2023	149	022
19 Dec 2023	149	026

Solar Active Regions and flaring

The solar flaring activity was at low levels, with several C-class flares recorded in the past 24 hours. The largest flare was a C8.4 flare, with peak time 13:54 UTC on December 16, associated with NOAA AR 3514 (beta-gamma). This region, that is rotating out of view over the west limb, is currently the most complex active region on the visible solar disc and was the main driver of the flaring activity observed over the past 24 hours. Low flaring activity was also produced by NOAA AR 3520 (beta). Other regions on the disc have simple configuration of their photospheric magnetic field (alpha and beta) and did not show any significant flaring activity. The solar flaring activity is expected to be at low to moderate levels over the next 24 hours with C-class flares expected, M-class flares possible and a low chance for isolated X-class flares.

Coronal mass ejections

No Earth directed Coronal Mass Ejections (CMEs) have been detected in the available coronagraph imagery.

Coronal holes

A positive polarity coronal hole in the northern hemisphere has fully transited the central meridian today.

Solar wind

At the beginning of the period, the solar wind parameters (ACE and DSCOVR) were reflecting the waning influence of an ICME. The solar wind speed decreased from values around 500 km/s to 450 km/s. The interplanetary magnetic field magnitude was below 8 nT. The southward component of the interplanetary magnetic field fluctuated between -8 nT and 5 nT. The magnetic field orientation was predominantly in the positive sector (field directed away from the Sun). At around 07:45 UTC on December 17 the magnetic field reached 16 nT (note the data gap in ACE and DSCOVR data, that occurred between 05:54 UTC and 07:32 UTC on December 17). The solar wind speed increased from 445 to 550 km/s. The southward interplanetary magnetic component, Bz, ranged between -11 nT and 15 nT. These disturbances most likely mark the arrival of the CMEs, that occurred on December 14-15. The solar wind conditions are expected to continue to be elevated due to the ICME passage with a chance of a week enhancement on December 18 – 19 due to the possible arrival of a high-speed stream from a positive polarity coronal hole.

Geomagnetism

The geomagnetic conditions over the past 24 hours reached minor storm levels globally (NOAA Kp 5) between 09:00 at 12:00 UTC on December 17 due to the ICME arrival. Locally, only quiet to unsettled (K-Bel=1-3) conditions were observed over Belgium. Geomagnetic conditions are expected to be at active levels, with a chance for isolated minor or moderate storm periods over the next 24 hours under the influence of an ongoing ICME arrival.

Proton flux levels

Over the past 24 hours, the greater than 10MeV proton flux has remained slightly elevated (peaking at 2.2 pfu) but below the event threshold, with a general decaying trend. The proton flux is expected to remain below the radiation storm threshold over the next 24 hours.

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux remained below the 1000 pfu threshold as measured by GOES 16. It is expected to remain below this threshold over the next days. The 24 hour electron fluence was at normal levels and is expected to remain so.

Today's estimated international sunspot number (ISN): 100, based on 11 stations.

Solar indices for 16 Dec 2023

Wolf number Catania	///
10cm solar flux	149
AK Chambon La Forêt	032
AK Wingst	022
Estimated Ap	019
Estimated international sunspot number	137 - Based on 12 stations

Noticeable events summary

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

All times in UTC

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