Viewing archive of Saturday, 16 December 2023

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2023 Dec 16 1231 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

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

Solar protons

Warning condition (activity levels expected to increase, but no numeric forecast given)

	10cm flux	Ap
16 Dec 2023	148	020
17 Dec 2023	150	030
18 Dec 2023	152	021

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 C5.5 flare, with peak time 21:29 UTC on December 15, associated with NOAA AR 3514 (beta-gamma). This region, which is presently approaching to the West solar 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 3513 (alpha). 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 M-class flares possible and a small chance for X-class flares.

Coronal mass ejections

A partial halo Coronal Mass Ejection (CME) was first observed in the SOHO/LASCO-C2 field of view at 07:48 UTC on December 15. The CME is likely associated with an M6.3 and an M6.9 flare, which peaked at 07:15 UTC and 07:34 UTC on December 15th, originating from NOAA AR 3514, along with a Type IV radio burst. The CME is directed primarily to the South-West from the Earth’s perspective and the bulk of the CME is not expected to be Earth directed. However, the CME has the potential of a glancing blow early on December 17, although with low confidence. No other Earth directed Coronal Mass Ejections (CMEs) have been detected in the available coronagraph imagery.

Coronal holes

A positive polarity coronal hole is continuing to cross the central meridian and a high-speed stream from this coronal hole may arrive to Earth from late on December 18.

Solar wind

Over the past 24 hours, the solar wind parameters were slightly disturbed under the ICME influence. The total magnetic field reached 23 nT at 14:30 UTC on December 15, later decreasing to the values around 9 nT. The solar wind speed ranged between 380 km/s and 520 km/s. The southward component of the interplanetary magnetic field fluctuated between -10 nT and 17 nT. The magnetic field orientation was predominantly in the positive sector (field directed away from the Sun). The solar wind conditions are expected to continue to be elevated due to the ICME passage with a chance of a week enhancement due to a possible glancing blow impact from the CMEs, that occurred on December 14 - 15.

Geomagnetism

The geomagnetic conditions over the past 24 hours were mostly unsettled (NOAA-Kp= 3) with a single active period registered globally (NOAA-Kp = 4) during the interval 03-06 UTC on Dec 16. Locally only quiet to unsettled (K-Bel=2-3) conditions were observed over Belgium. Geomagnetic conditions are expected to be at unsettled to active levels, with a chance for isolated minor storm periods on Dec 16 - 17 due to CMEs from December 14-15th which may have a glancing blow at Earth.

Proton flux levels

The greater than 10 MeV proton flux has crossed the 10 pfu threshold level at 23:35 UTC on December 15. It stayed above the threshold level until 00:55 UTC on December 15. The greater than 10 MeV proton flux is expected to remain enhanced, with a chance that a particle event occurs following the arrival of CMEs from December 14 – 15.

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): 128, based on 06 stations.

Solar indices for 15 Dec 2023

Wolf number Catania	133
10cm solar flux	144
AK Chambon La Forêt	026
AK Wingst	013
Estimated Ap	013
Estimated international sunspot number	121 - 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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