Viewing archive of Wednesday, 20 September 2023

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2023 Sep 20 1231 UTC

SIDC Forecast

Solar flares

M-class flares expected (probability >=50%)

Geomagnetism

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

Solar protons

Quiet

	10cm flux	Ap
20 Sep 2023	166	015
21 Sep 2023	168	018
22 Sep 2023	170	007

Solar Active Regions and flaring

There are ten active regions visible on the disk. The strongest flare of the last 24 hours was an M4.0 one from NOAA AR 3435, peaking at 20:14 UTC on 19 September. This region has developed into a beta-delta region, also NOAA ARs 3436 and 3438 have evolved in complexity (now beta-gamma magnetic field configuration). More M-class flares can be expected in the next 24 hours, X-class flares are possible but less likely.

Coronal mass ejections

No Earth directed CMEs were observed in the last 24 hours.

Coronal holes

There are two small negative coronal holes crossing the central meridian, one at the equator and one in the northern hemisphere.

Solar wind

In the last 24 hours, the Earth has been inside the influence of ICME and high speed solar wind, with interplanetary magnetic field reaching 11 nT (Bz down to -7 nT) and solar wind speed descending from 620 km/’s to 520 km/s.A gradual decrease into slow solar wind is expected, until the probable arrival of the CME from 17 september in about 24 hours. More disturbed solar wind conditions can be expected if the ICME arrives (although chances of this happening are low).

Geomagnetism

During the last 24 hours the geomagnetic conditions have reached minor storm levels globally (NOAA KP 5) and active levels locally (K_Bel 4), due to the ICME and high speed solar wind combination. The situation is expected to subside gradually, but more disturbed periods can be expected if the CME from 17 September arrives in about 24 hours.

Proton flux levels

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

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux went above the 1000 pfu threshold during brief instants between 15:00 UTC on 19 September until 01:00 UTC on 20 September, as measured by GOES 16. It may increase over the threshold again in the next 24 hours. The 24 hour electron fluence increased from normal to moderate level, it is expected to stay at that levels for the next 24 hours.

Today's estimated international sunspot number (ISN): 179, based on 12 stations.

Solar indices for 19 Sep 2023

Wolf number Catania	189
10cm solar flux	166
AK Chambon La Forêt	038
AK Wingst	040
Estimated Ap	040
Estimated international sunspot number	164 - Based on 21 stations

Noticeable events summary

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

All times in UTC

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