Viewing archive of Wednesday, 13 September 2023

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2023 Sep 13 1234 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Quiet

	10cm flux	Ap
13 Sep 2023	164	007
14 Sep 2023	164	014
15 Sep 2023	164	008

Solar Active Regions and flaring

The solar flaring activity was at quiet levels over the past 24 hours with several C-class flares from various sunspot groups. The larger flare was a C5.5-class flare occurring today at 08:10 UTC in NOAA Active Region 3423. The most complex regions with a beta-gamma magnetic configuration are NOAA Active Region 3423 and 3425.The other regions are unipolar or bipolar with an alpha or beta magnetic configuration. The flaring activity is expected to remain at quiet levels with C-class flares with possible isolated M-class flares. X-class flare are also possible due to the high magnetic complexity of the and the fast evolution of some regions.

Coronal mass ejections

No clear Earth-directed Coronal Mass Ejections (CME) was observed in the SOHO/LASCO coronograph images over the past 24 hours.

Coronal holes

An equatorial polar coronal hole (with a negative magnetic polarity) has now fully transited the central meridian. The high-speed streams associated to this equatorial coronal hole is expected to reach Earth in 1-2 days.

Solar wind

The solar wind conditions were strongly enhanced over the past 24 hours, due to the passage of a relatively slow solar structure (with a maximum speed of 440 km/s). A solar wind shock was observed on September 12 at 11:22 UTC in the solar wind parameters recorded by DSCOVR. The total interplanetary magnetic field (Bt) jumped from 11 nT to 18 nT, the solar wind speed also jumped from 361 km/s to 409 km/s. The signature of the solar wind shock was also visible in the southward component (Bz) and the solar wind density. Then, the total interplanetary magnetic field (Bt) increased up to 20 nT, the southward component (Bz) reached -19 nT, and the solar wind speed rose up to 440 km/s. This solar wind structure may be associated with the arrival of the faint halo coronal mass ejection (CME) that was observed on September 07. Now, the solar wind parameters have returned to a slow solar wind regime: The wind speed is ranging from 416 km/s and 446 km/s. The total interplanetary magnetic field (Bt) has decreased to values below 10 nT. The southward component (Bz) is fluctuating between -6.7 nT and 5.5 nT. The solar wind parameters are expected to remain in the slow solar wind regime for the next 24 hours then the solar wind speed is expected to later due to the high-speed streams associated with the equatorial coronal hole (negative magnetic polarity) that has reached the central meridian on September 11.

Geomagnetism

Following the solar wind enhancement, a geomagnetic storm was observed (Kp=6- and K_BEL=5) on September 12 at 15:00 UTC. Geomagnetic activity is expected to be mostly quiet to unsettled for the next 24 hours.

Proton flux levels

The greater than 10 MeV proton flux was at background levels over the past 24 hours and is expected to remain so for the next 24 hours.

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux was below the 1000 pfu threshold. It is expected to remain below the threshold for the next 24 hours. The 24-hour electron fluence was at normal levels for the past 24 hours and it is expected to remain at these levels for the next 24 hours.

Today's estimated international sunspot number (ISN): 139, based on 16 stations.

Solar indices for 12 Sep 2023

Wolf number Catania	173
10cm solar flux	154
AK Chambon La Forêt	046
AK Wingst	021
Estimated Ap	025
Estimated international sunspot number	162 - Based on 23 stations

Noticeable events summary

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

All times in UTC

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