Viewing archive of Saturday, 18 September 2021

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2021 Sep 18 1231 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Quiet

	10cm flux	Ap
18 Sep 2021	074	011
19 Sep 2021	076	004
20 Sep 2021	078	001

Bulletin

The solar activity was at low levels with only one detection of a C2.6 flare during the last 24 hours. There are currently no Active Regions (AR) visible from Earth, however the C-class activity came at 08:33 UT from an AR expected to soon turn into view. NOAA plage 2870 is also present on the front side of the solar disk, but did not produce any noticeable activity. For the next 24 hours more C-class activity is likely and an M-class flare is possible from the same AR, however it is difficult to provide a reliable estimation as its magnetic complexity is currently unknown.

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.

The Solar Wind (SW) parameters as observed by ACE and DSCOVR are affected again from the CME observed in 13 Sep 12:00 UT. The SW speed gradually increased from 320 to 420 km/s during the last 24 hours. The total magnetic field (Btot) varied between 2.3 and 15.2 nT, while its Bz component between -13.5 and 11.6 nT. The interplanetary magnetic field phi angle was predominantly in the positive sector (directed away from the Sun) until today 04:00 UT and has turned negative since. The SW conditions are expected to gradually return to a slow wind regime, unless another component of the CME of the 13 Sep arrives.

The geomagnetic conditions over the past 24 hours were globally quiet (NOAA Kp index 1-2) and locally quiet to active (K Dourbes 1-4). In the next 24 hours they are expected to become quiet both globally and locally.

Today's estimated international sunspot number (ISN): 000, based on 23 stations.

Solar indices for 17 Sep 2021

Wolf number Catania	000
10cm solar flux	073
AK Chambon La Forêt	039
AK Wingst	026
Estimated Ap	028
Estimated international sunspot number	000 - Based on 27 stations

Noticeable events summary

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

All times in UTC

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