Viewing archive of Friday, 15 December 2023

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2023 Dec 15 1232 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
15 Dec 2023	150	021
16 Dec 2023	152	025
17 Dec 2023	150	018

Solar Active Regions and flaring

Solar flaring activity reached high levels over the past 24 hours. The largest flare was a X2.8 flare, with peak time 17:02 UTC on December 14, associated with NOAA AR 3514 (beta- delta) in the northwest of the solar disk. Type II and Type IV radio emission were detected at 17:08 during the flaring activity. NOAA AR 3514 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. The region also produced M6.3 and M6.9 flares with peak time at 07:15 UTC and 07:34 UTC on December 15th. 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 moderate levels over the next 24 hours with M-class flares possible and a small chance for X-class flares.

Coronal mass ejections

A faint CME was observed in SOHO/LASCO-C2 at around 07:39 UTC on December 14, directed towards the North-West from Earth perspective. The coronal mass ejection is likely associated to M5.8 flare from NOAA AR 3514 and a small coronal dimming. A halo coronal mass ejection (CME) was observed in LASCO/C2 coronagraph data from 17:24 UTC on December 14. The CME is associated with a X2.8 flare, originating from NOAA AR 3514, along with a Type II and Type IV radio burst. The CME is directed primarily to the West from the Earth perspective. As the later CME is much faster than the former, they are expected to merge into each other. Due to the location of CMEs origin, a glancing blow to the Earth's environment can be possible late on December 16 – early on December 17. Also, the M6.3-flare that occurred today were accompanied by Type-IV bursts (as measured by the Humain Radioastronomy Station), no coronagraph data are available yet to confirm the presence of CMEs.

Coronal holes

A positive polarity coronal hole in the northern hemisphere has now reached the central median.

Solar wind

At the beginning of the period, the solar wind parameters (ACE, SOHO) were reflecting near slow solar wind conditions. The solar wind speed was approximately 280 km/s; the total interplanetary magnetic field was below 5 nT. A shock was observed in the solar wind parameters at around 10:57 UTC on December 15. The interplanetary magnetic field jumped from 5 nT to 19 nT. The solar wind velocity increased from 280 km/s to 411 km/s. It is not clear which of the events from the past days may be responsible for this shock arrival, but it may be associated to the faint partial halo CME observed on December 13. The solar wind conditions are expected to continue to be elevated due to the ICME passage with a chance of a week enhancement on Dec 15-17 due to the possible arrival of a high-speed stream from a small positive polarity coronal hole and a chance of glancing blow impact from the CMEs, that occurred on December 14.

Geomagnetism

The geomagnetic conditions over the past 24 hours were mostly quiet to unsettled (NOAA-Kp=1-3). Locally only quiet (K-Bel=1-2) conditions were observed over Belgium. Geomagnetic conditions are expected to be at unsettled to active levels, with a chance for isolated minor storm period on Dec 15 - 17 with expected high speed stream arrival from a small positive polarity coronal hole and possible CME arrivals.

Proton flux levels

In the past 24 hours the greater than 10 MeV proton flux enhanced but remains under the 10 pfu threshold over the past 24 hours. The enhancement was likely associated with the CME detected in LASCO/C2 coronagraph data from 17:24 UTC on December 14. The greater than 10 MeV proton flux is expected to remain below the radiation storm threshold over the next 24 hours, with a small chance that a particle event occurs in association with an X-class flare or a coronal mass ejection.

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): 109, based on 06 stations.

Solar indices for 14 Dec 2023

Wolf number Catania	139
10cm solar flux	155
AK Chambon La Forêt	014
AK Wingst	014
Estimated Ap	015
Estimated international sunspot number	122 - Based on 16 stations

Noticeable events summary

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

All times in UTC

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