Viewing archive of Saturday, 16 September 2023

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2023 Sep 16 1231 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Active conditions expected (A>=20 or K=4)

Solar protons

Quiet

	10cm flux	Ap
16 Sep 2023	141	011
17 Sep 2023	141	016
18 Sep 2023	141	010

Solar Active Regions and flaring

The solar flaring activity was at moderate levels, with three M-class flares and several C-class flares recorded in the past 24 hours. The largest flares of the period were an M3.3 flare, peaking at 05:38 UTC on Sept 16, an M2.9 flare, peaking at 00:50 UTC on Sept 16, and an M1.7 flare, peaking at 22:29 UTC on Sept 15, associated with NOAA AR 3429 (beta-gamma-delta class). This region is currently the most complex active region on the disk and was the main driver of the flaring activity observed over the past 24 hours. Isolated C-class flaring was also prodiced by new AR rotating into view over the east limb. 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 likely and M-class flares possible.

Coronal mass ejections

A faint coronal mass ejection (CME) was observed in LASCO/C2 coronagraph data from 23:12 UTC on Sept 14. The CME was probably associated with an M2.5 flare originating from NOAA AR 3429. The CME is directed to the south-east and the bulk of the CME is not expected to be Earth directed. However, a glancing blow of the shock is possible on Sept 18, although with low confidence. A large filament eruption occured in the central-north part of the Sun near NOAA AR 3429 and NOAA AR 3434 from around 04:13 UTC on Sept 16th. The associated halo CME was first observed in SOHO/LASCO-C2 coronagraph data from 09:12 UTC on Sept 16th. The CME is directed to the south-west; further analysis is on-going to better determine the expected impacts.

Solar wind

Over the past 24 hours the solar wind parameters (ACE and DSCOVR) reflected the waning influence of the high-speed stream. The solar wind speed decreased from 490 km/s to the values around 430 km/s. The interplanetary magnetic field magnitude was below 6 nT. The southward component of the interplanetary magnetic field fluctuated between -5 nT and 5 nT. The magnetic field orientation was predominantly in the negative sector (field directed towards the Sun). Similar conditions are expected for the next 24 hours, with a further enhancement possible on Sept 16 – Sept 17 due to the predicted arrival of CME from Sept 14.

Geomagnetism

The geomagnetic conditions over the past 24 hours were quiet to unsettled (NOAA-Kp=1-3, K-Bel=1-3). Geomagnetic conditions are expected to be at quiet to unsettled levels, with a chance of increasing to active conditions and isolated minor storm periods from late on Sept 16 - early on Sept 17, due to a possible arrival of the CME from Sept 14.

Proton flux levels

The greater than 10 MeV proton was at the nominal levels in the past 24 hours. The proton flux is expected to remain below 10 pfu threshold over the next day, 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, as measured by the GOES-16 satellite, was below the 1000 pfu threshold and is expected to remain below this threshold for the next days.The 24h electron fluence was at normal level. The electron fluence is expected to be at normal levels in the next days.

Today's estimated international sunspot number (ISN): 096, based on 15 stations.

Solar indices for 15 Sep 2023

Wolf number Catania	133
10cm solar flux	139
AK Chambon La Forêt	011
AK Wingst	007
Estimated Ap	007
Estimated international sunspot number	123 - Based on 22 stations

Noticeable events summary

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

All times in UTC

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