Viewing archive of Monday, 27 September 2021

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2021 Sep 27 1231 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

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

Solar protons

Quiet

	10cm flux	Ap
27 Sep 2021	086	007
28 Sep 2021	086	007
29 Sep 2021	086	007

Bulletin

Four active regions (ARs) present on the visible solar disk. No flares above the B-class level in the past 24 hours. Over the next 24 hours, C-class flares can be expected, in particular from NOAA AR 2871 which has a beta-gamma magnetic field configuration (the other 3 ARs have a beta magnetic field configuration).

No Earth directed CMEs have been observed in coronagraph data in the last 24 hours.

The greater than 10 MeV proton flux was at background levels in the past 24 hours, and is expected to stay there in the next 24 hours. The greater than 2 MeV electron flux remained below the 1000 pfu alert threshold. Over the next 24 hours, it is expected to remain below the threshold. The electron fluence was at normal levels over the past 24 hours, and is expected to remain so for the next 24 hours.

Over the past 24 hours the solar wind speed has been around 400 km/s. The total magnetic field strength had reached 11 nT, while its Bz component reached -6 nT. This slightly elevated magnetic field, together with low temperature plasma, could mark the expected arrival of the ICMEs from 23 and 24 September. Due to the low speeds and mostly positive Bz, the effect is very mild, the situation may change in the coming hours since more than one ICME was expected.

Geomagnetic conditions were quiet to unsettled (NOAA Kp and K Dourbes 1-3) over the past 24 hours. Active periods can be expected over the next 24 hours.

Today's estimated international sunspot number (ISN): 049, based on 10 stations.

Solar indices for 26 Sep 2021

Wolf number Catania	///
10cm solar flux	086
AK Chambon La Forêt	006
AK Wingst	002
Estimated Ap	001
Estimated international sunspot number	048 - Based on 26 stations

Noticeable events summary

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

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