Viewing archive of Thursday, 21 September 2023

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2023 Sep 21 1231 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Quiet

	10cm flux	Ap
21 Sep 2023	156	008
22 Sep 2023	158	007
23 Sep 2023	160	007

Solar Active Regions and flaring

There are eleven active regions visible on the disk. The strongest flare of the last 24 hours was an M8.2 one from NOAA AR 3435 (beta-delta magnetic field configuration), peaking at 14:19 UTC on 20 September. All the other regions have simpler alpha or beta 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

A partial halo CME with angular width around 150 degrees was first seen at 06:12 UTC on 20 September by LASCO-C2. The CME originated in a region at the east limb, and the bulk of the material was traveling to the east. The CME was slow (speed around 350 km/s), no effect is expected at the Earth.

A second (faint) partial halo CME with angular width around 180 degrees was first seen at 14:12 UTC on 20 September by LASCO-C2. The CME was related to the M8.2 flare from NOAA AR 3435, the bulk of the material was traveling to the south. The CME had a speed around 800 km/s, an impact at the Earth can be expected on 23 September.

Coronal holes

Two small negative coronal holes crossed the central meridian yesterday, one at the equator and one in the northern hemisphere. A possible mild high speed stream may arrive to the Earth in 48 hours.

Solar wind

In the last 24 hours, the solar wind speed at the Earth has decreased to 430 km/s, and the interplanetary magnetic field has decreased to 4 nT. Similar slow solar wind conditions can be expected for the next 24 hours, unless we observe the (unlikely) arrival of the 17 and 18 September CMEs.

Geomagnetism

During the last 24 hours the geomagnetic conditions have reached active levels globally (NOAA KP 4) and unsettled levels locally (K_Bel 3). Mostly quiet to unsettled conditions can be expected in the next 24 hours, with possible active to minor storm levels if the CMEs from 17 and 18 September arrive.

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 between 13:00 UTC and 20:00 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 was at moderate levels, it is expected to stay at those levels for the next 24 hours.

Today's estimated international sunspot number (ISN): 197, based on 07 stations.

Solar indices for 20 Sep 2023

Wolf number Catania	///
10cm solar flux	156
AK Chambon La Forêt	017
AK Wingst	018
Estimated Ap	018
Estimated international sunspot number	179 - Based on 19 stations

Noticeable events summary

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

All times in UTC

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