Viewing archive of Wednesday, 6 September 2023

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2023 Sep 06 1258 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Quiet

	10cm flux	Ap
06 Sep 2023	147	009
07 Sep 2023	150	017
08 Sep 2023	152	008

Solar Active Regions and flaring

During the last 24 hours number of C-class and two M-class flares were reported. Majority of the flaring activity, including two M-class flares, originated from the Catania sunspot group 41 (NOAA AR 3421). The strongest out of reported flares was M1.2 flare which peak at 19:45 UT on September 05. Two complex active regions, NOAA AR 3423 and NOAA AR 3424, which rotated to the visible side of the Sun are expected to be the additional sources of the flaring activity in the coming hours. We expect flaring activity of the C-class and also M-class level in the following days.

Coronal mass ejections

During last 24 hours several wide CMEs were detected in the available coronagraph data. The full halo CME, first time seen in the SOHO/LASCO C2 field of view at about 14:00 UT on September 05, had velocity of about 1000 km/s (as reported by CACTUS software). Presently available observations indicate that its source region was probably situated at, and behind the West solar limb. Due to the position of CME's source region we do not expected this CME to arrive to Earth.

The M1.2 flare (peaked at 19:45 UT on September 05) originating from the Catania sunspot group 41 (NOAA AR 3421), was associated with the full halo CME. The CME was first time seen in the SOHO/LASCO C2 field of view at about 20:24 UT on September 05. The CME had velocity of about 1300 km/s (as reported by the CACTUS software), and it is possible that, due to its large width and source region situated at the center of the solar disc, it will arrive to Earth. The expected arrival time of this CME at Earth is in the early afternoon of September 07.

Coronal holes

The small, negative polarity coronal hole is presently crossing central meridian. The associated solar wind could arrive to Earth on midday of September 09.

Solar wind

The in situ data show the sudden simultaneous jump of the solar wind magnetic field, velocity, density and temperature, indicating arrival of the shock wave, at about 14:40 UT on September 06. The observed shock is possibly associated with the late arrival of the halo CME first seen in the SOHO/LASCO C2 field of view at 04:17 UT on September 01. The shock wave was followed by two longer intervals of the negative value of the Bz component of the interplanetary magnetic field magnitude (down to -9 nT) which resulted in disturbed geomagnetic condition. The shock was followed only by the post shock sheath-region but presently no clear signatures of ICME are visible in the in situ observations. The solar wind speed is presently around 400 km/s and the interplanetary magnetic field magnitude is about 5 nT.

Geomagnetism

During last 24 hours the geomagnetic conditions were active to unsettled, due to the arrival of a shock wave. The solar wind originating from the negative polarity coronal hole which crossed central meridian on September 03 can be expected at Earth in the morning of September 07, and it can cause unsettled to active geomagnetic conditions.

Proton flux levels

The greater than 10 MeV proton flux was at the background levels and we do not expect significant change in the coming hours. As the complex Catania sunspot group 41 (NOAA AR 3421) is approaching to the West solar limb, the strong flaring activity could be, in about two days from now, associated with the particle event.

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux has continue to fluctuate around the 1000 pfu threshold. The 24h electron fluence is at normal level. We do not expect significant change in these three parameters in the coming 24 hours.

Today's estimated international sunspot number (ISN): 133, based on 24 stations.

Solar indices for 05 Sep 2023

Wolf number Catania	///
10cm solar flux	143
AK Chambon La Forêt	020
AK Wingst	010
Estimated Ap	011
Estimated international sunspot number	124 - Based on 30 stations

Noticeable events summary

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

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