Viewing archive of Tuesday, 7 September 2021

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2021 Sep 07 1230 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Quiet

	10cm flux	Ap
07 Sep 2021	102	009
08 Sep 2021	098	007
09 Sep 2021	098	011

Bulletin

Solar activity was at very low to low levels over the past 24 hours with a single C1.1 class flare from NOAA 2866 (peak time 09:34 UTC on Sept 07th). The solar disc remains with the four numbered active regions reported yesterday. All regions have magnetic type beta with NOAA 2866 being the most complex and the most active region so far. The X-ray flaring activity is expected to be at very low to low levels for the next 24 hours with 55% probability for C-class flaring.

The slow and weak CME driven by a B-class flare from active region NOAA 2864 and visible in the coronagraph images around 21:15 UTC on Sept 04th could have an Earth-directed component with an expected arrival in the early evening of Sept 09th. A filament eruption near the neighbouring plage region (previously NOAA 2865) and further high B-class flaring from it in the evening of Sept 05th resulted in a very faint partial halo CME as observed by LASCO C2. A glancing blow from this CME could arrive to the Earth on Sept 10th. Nevertheless, considering that this was a very faint and slow eruption, no significant impact is expected. No other Earth- directed CMEs were observed in the available coronagraph imagery.

The greater than 10 MeV proton flux was at nominal levels in the past 24 hours and is expected to remain so in the next 24 hours. The greater than 2MeV electron flux was predominantly below the 1000 pfu threshold with a single period above the threshold between 14:00 and 18:00 UTC on Sept 06th. The 2MeV electron flux is expected to remain predominantly below the 1000 pfu threshold with isolated periods above the threshold. The 24h electron fluence was at the border of moderate and nominal levels and is expected to return to nominal levels in the next 24 hours.

Over the past 24 hours all solar wind parameters (ACE and DSCOVR) were at very low levels. The solar wind speed was in the range of 286 to 330 km/s. The total magnetic field was weak with values between 2 and 5.8 nT. The Bz component varied weakly in the range of -5.3 to +2.8 nT. The interplanetary magnetic field was predominantly in the positive sector (directed away from the Sun).

The geomagnetic conditions over the past 24 hours were globally quiet with a single unsettled period and locally mostly quiet with several isolated unsettled periods. Mostly quiet geomagnetic conditions are expected for the next 24 hours with the possibility for isolated unsettled periods. Unsettled geomagnetic conditions with active periods can be expected late on Sept 09th should the slow CME launched from the Sun on Sept 05th reach the Earth.

Today's estimated international sunspot number (ISN): 082, based on 20 stations.

Solar indices for 06 Sep 2021

Wolf number Catania	///
10cm solar flux	100
AK Chambon La Forêt	012
AK Wingst	008
Estimated Ap	009
Estimated international sunspot number	084 - 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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