Viewing archive of Sunday, 17 September 2023

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2023 Sep 17 1304 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

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

Solar protons

Warning condition (activity levels expected to increase, but no numeric forecast given)

	10cm flux	Ap
17 Sep 2023	140	015
18 Sep 2023	138	005
19 Sep 2023	136	021

Solar Active Regions and flaring

Solar flaring activity was at low levels in the past 24 hours with background low C-class flaring. The strongest activity was a C3.7-class flare produced by active region NOAA AR 3429 (beta-gamma), which is the most complex region on the visible solar disc and is responsible for most of the flaring activity. Isolated low C-class flaring was produced by NOAA 3435 (beta), which has rotated into view from the east limb, as well as from a region behind the south-east limb. The remaining four active regions are relatively simple and have either shown some decay or remained stable and inactive. The solar flaring activity is expected to be at low levels over the coming days with likely C-class flares and low chances for isolated M-class flaring.

Coronal mass ejections

The halo coronal mass ejection (CME) related to the large filament eruption near the disc centre on Sept 16th, which was first observed by SOHO/LASCO-C2 at 09:12 UTC has now been analysed. While the bulk of the CME travels westward, a flank/glancing blow is expected to reach Earth on Sept 19th. No new Earth-directed CMEs have been detected in the available coronagraph imagery.

Coronal holes

A small mid-latitude negative polarity coronal hole has crossed the central meridian in the UTC afternoon of Sept 16th and could cause some enhanced solar wind conditions at Earth earliest on Sept 19th.

Solar wind

Over the past 24 hours the solar wind parameters (ACE and DSCOVR) have registered minor enhancements possibly due to an expected high speed stream arrival travelling in the perturbed solar wind conditions from the nearby passage of the Sept 14th CME. The solar wind velocity has reached 500 km/s. The interplanetary magnetic field reached 11.3 nT with a minimum Bz of -8.7 nT. The B field was highly fluctuating, remaining predominantly in the negative sector (directed towards the Sun). The solar wind conditions are expected to remain perturbed with further possible enhancements due to the expected arrival of the Sept 14th CME. Further enhancements in the solar wind are expected on Sept 19th with probable arrival of the Sept 16th CME and a possible mild high speed stream from the negative polarity coronal hole, which crossed the central meridian on Sept 16th.

Geomagnetism

The geomagnetic conditions over the past 24 hours were quiet to active. Quiet to unsettled geomagnetic conditions are expected to prevail throughout Sept 17th with some chances for isolated active conditions small chances for minor geomagnetic storms. Mostly quiet to unsettled conditions are expected for Sept 18th and quiet conditions to minor storm levels are anticipated on Sept 19th with the expected arrival of the Sept 16th halo CME and possible mild high speed stream.

Proton flux levels

Over the past 24 hours the greater than 10 MeV GOES proton flux was at background levels and is expected to continue so over the next days.

Electron fluxes at geostationary orbit

The greater than 2 MeV GOES 16 electron flux was below the 1000 pfu threshold and is expected to remain so in the upcoming days.The 24h electron fluence was at nominal level and is expected to remain so in the next days.

Today's estimated international sunspot number (ISN): 096, based on 12 stations.

Solar indices for 16 Sep 2023

Wolf number Catania	///
10cm solar flux	140
AK Chambon La Forêt	021
AK Wingst	010
Estimated Ap	008
Estimated international sunspot number	096 - 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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