Viewing archive of Tuesday, 19 September 2023

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2023 Sep 19 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
19 Sep 2023	155	022
20 Sep 2023	157	007
21 Sep 2023	158	007

Solar Active Regions and flaring

There are nine active regions visible on the disk. There have been two M-class flares in the last 24 hours, from NOAA AR 3435. The strongest was an M1.9 flare occurring at 09:38 UTC (peak). This region and NOAA AR 3436 have increased in size and complexity and can produce more M-class flares in the next 24 hours.

Coronal mass ejections

A partial halo CME with angular width around 150 degrees was first seen at 11:12 UTC on 18 September by LASCO-C2. The CME most likely originated (the eruption signatures are weak) in the vicinity of NOAA AR 3436 in the NW quadrant, it was slow (around 300 km/s) and mostly directed to the NW. Nevertheless, a glancing blow at the Earth can not be discarded on 22 September.

Solar wind

A shock was observed in DSCOVR data on 18 September at 12:57 UTC. The magnetic field jumped from 9 to 22 nT, and the solar wind speed from 420 to 550 km/s. This marks an early arrival of the 16 September CME. Later on, the solar wind speed surpassed the 600 km/s and the interplanetary magnetic field reached to 22 nT, with Bz down to -17 nT. We probably observed also some combined effects from a high speed solar wind stream. More disturbed solar wind conditions can be expected in the next 24 hours.

Geomagnetism

During the last 24 hours the geomagnetic conditions have reached moderate storm levels globally (NOAA KP 6) and minor storm levels locally (K_Bel 5), due to the ICME arrival (from the CME on 16 September). The situation is expected to subside gradually, but more disturbed periods can be expected in the next 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 remained below the 1000 pfu threshold as measured by GOES 16. They may increase over the threshold in the next 24 hours. The 24 hour electron fluence was at normal levels and it could also increase in the next 24 hours.

Today's estimated international sunspot number (ISN): 158, based on 13 stations.

Solar indices for 18 Sep 2023

Wolf number Catania	170
10cm solar flux	155
AK Chambon La Forêt	044
AK Wingst	031
Estimated Ap	030
Estimated international sunspot number	130 - Based on 24 stations

Noticeable events summary

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

All times in UTC

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