Viewing archive of Saturday, 11 September 2021

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2021 Sep 11 1236 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Quiet

	10cm flux	Ap
11 Sep 2021	094	009
12 Sep 2021	094	015
13 Sep 2021	092	005

Bulletin

The solar activity was at low levels with a single C-class flare over the past 24 hours. There are currently five active regions on the visible solar disc. NOAA 2868/Catania 39 (beta-gamma) retained its magnetic complexity and produced a long-duration C1.1-class flare (peak time 21:34 UTC on Sept 10th). NOAA 2866/Catania 40 (beta) started to decrease in size and sunspot numbers. NOAA 2864/Catania 38 is now classified as beta, but has remained quiet and will soon rotate over the west limb together with NOAA 2863/Catania 37 (alpha). NOAA 2869/Catania 41 (beta) remained stable with no signs of development. NOAA 2870/Catania 42 has now decayed into plage. The X-ray flare activity is expected to be at very low to low levels for the next 24 hours with remaining significant change for C-class flaring and a minor chance for M-class flaring from NOAA 2868.

No Earth-directed CMEs were detected in the available coronagraph imagery over the past 24 hours.

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 below the 1000 pfu threshold and is expected to remain so in the next 24 hours. The 24h fluence for the greater than 2MeV electron flux was at nominal levels and is expected to remain so in the next 24 hours.

Over the past 24 hours the solar wind parameters (ACE and DSCOVR) have returned back to slow solar wind conditions after the passage of the ICME, which ended around 23:00 UTC on Sept 10th. The solar wind speed remained low throughout the entire interval varying in the range of 310 to 380 km/s. The total magnetic field was elevated with values between 9 to 13.6 nT. The Bz component was mostly positive with a longer interval of low negative values between 18:00 and 23:00 UTC and a peak of - 10.5 nT during the end of the magnetic cloud passage. The interplanetary magnetic field was mostly in the positive sector.

The geomagnetic conditions over the past 24 hours were globally quiet to active and locally quiet to unsettled. Mostly quiet to unsettled geomagnetic conditions are expected for the next 24 hours with possible isolated active periods towards the early morning of Sept 12th due to the glancing blow from the slow CME which left the Sun around 00:36 UTC on Sept 8th. Unsettled conditions could be expected on Sept 12th with the possible arrival of some high speed stream originating from a rather small positive polarity mid-latitude coronal hole, which crossed the central meridian on Sept 9th.

Today's estimated international sunspot number (ISN): 080, based on 07 stations.

Solar indices for 10 Sep 2021

Wolf number Catania	///
10cm solar flux	096
AK Chambon La Forêt	021
AK Wingst	010
Estimated Ap	011
Estimated international sunspot number	093 - Based on 20 stations

Noticeable events summary

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

All times in UTC

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