Viewing archive of Thursday, 7 October 2021

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2021 Oct 07 1231 UTC

SIDC Forecast

Solar flares

Quiet conditions (<50% probability of C-class flares)

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Quiet

	10cm flux	Ap
07 Oct 2021	086	005
08 Oct 2021	086	005
09 Oct 2021	086	007

Bulletin

Two sunspot groups are visible on the solar surface seen from Earth (Catania sunspots group 54, NOAA AR-2880 and Catania sunspots group 58, NOAA AR-2882). The Catania sunspot group 58 (NOAA AR-2882) grew and become more complex over the past 24 hours. Its magnetic complexity changed from Alpha to Beta-Gamma, and a C5.5-class flare was observed today on Oct 7 peaking at 02.46 UTC. The new unipolar sunspot groups (Catania sunspot group 59) was short-lived and has fully decayed. More C-class flare are expected coming from Catania sunspot group 58 (NOAA AR-2882) with small chance of M-class flare.

No Earth directed Coronal Mass Ejection (CME) has been observed in the available coronagraph imagery.

The greater than 10 MeV proton flux was at nominal levels in the past 24 hours, and is expected to stay at nominal levels in the next 24 hours. The greater than 2 MeV electron flux was below the 1000 pfu and at nominal levels in the past 24 hours, and is expected to stay at nominal levels in the next 24 hours. The greater than 2 MeV electron fluence was at nominal levels in the past 24 hours, and is expected to stay at nominal levels in the next 24 hours.

The Earth remained under the slow solar wind speed regime (ranging between 289 km/s and 340 km/) over the past 24 hours. The solar wind parameters (as observed by ACE and DSCOVR) showed mostly an ambient background solar wind flow except for the interplanetary magnetic field. The interplanetary magnetic field magnitude was enhanced and ranged between 6.4 nT and 12.0 nT with its Bz components fluctuating between -9.9 nT and 9.9 nT. This enhancement is probably due the passage of a transient solar wind structure flowing at the same speed as the background wind. Mostly nominal solar wind regime is expected to persist in the next 24 hours.

In response to the enhanced interplanetary magnetic field and its southward directed Bz component reaching -9.9 nT, the geomagnetic conditions were unsettled to active during the first part of the 24-hour period (values of K-Dourbes index were between 2 and 4, and NOAA-Kp index between 1 and 3). Then from Oct 6 at 22:00 UTC, the geomagnetic conditions returned quiet and is expected to remain quiet as long as the Earth remains in slow solar wind speed regime.

Today's estimated international sunspot number (ISN): 016, based on 16 stations.

Solar indices for 06 Oct 2021

Wolf number Catania	///
10cm solar flux	085
AK Chambon La Forêt	011
AK Wingst	008
Estimated Ap	009
Estimated international sunspot number	025 - Based on 14 stations

Noticeable events summary

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

All times in UTC

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