Viewing archive of Saturday, 23 September 2023

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2023 Sep 23 1231 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Minor storm expected (A>=30 or K=5)

Solar protons

Quiet

	10cm flux	Ap
23 Sep 2023	176	013
24 Sep 2023	176	023
25 Sep 2023	176	019

Solar Active Regions and flaring

There are twelve active regions visible on the disk. There were three M-class flares in the last 24 hours, the strongest one was an M1.9 from NOAA AR 3435 (beta magnetic field configuration), peaking at 23:00 UTC on 22 September. The other two M_class flares were produced by the new NOAA ARs 3443 (beta-gamma magnetic field configuration). 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 wide CME with angular width around 90 degrees was first seen by LASCO-C2 at 02:24 UTC on 22 September. The CME was related to the M1.2 flare from NOAA AR 3435. The CME speed was estimated to be around 730 km/s, with the bulk of the material directed to the NE. Since the source is located close to disk center, an impact at Earth can be expected on 24 September(this ICME will probably interact with the one from 21 September on its way to the Earth).

Coronal holes

There are two small negative coronal holes that crossed the central meridian on 20 September, one at the equator and one in the northern hemisphere.

Solar wind

In the last 24 hours, the solar wind speed at the Earth has been around 400 km/s and the interplanetary magnetic field around 5 nT. Similar slow solar wind conditions can be expected for the next 24 hours. Nevertheless, the CME from 20 September can arrive to the Earth and change the solar wind conditions. Furthermore, we may observe the arrival of a (mild) high speed stream from the two coronal holes that traversed the central meridian on 20 September.

Geomagnetism

During the last 24 hours the geomagnetic conditions have been quiet to unsettled, both globally and locally (NOAA KP 3, K_Bel 3). Geomagnetic conditions are expected to reach minor to moderate storm levels if the expected CMEs and high speed streams 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 was above the 1000 pfu, as measured by GOES 16. It has gone down in the last hours, but 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): 214, based on 13 stations.

Solar indices for 22 Sep 2023

Wolf number Catania	239
10cm solar flux	176
AK Chambon La Forêt	021
AK Wingst	010
Estimated Ap	011
Estimated international sunspot number	221 - Based on 16 stations

Noticeable events summary

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

All times in UTC

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