Viewing archive of Thursday, 21 October 2021

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2021 Oct 21 1231 UTC

SIDC Forecast

Solar flares

Quiet conditions (<50% probability of C-class flares)

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Quiet

	10cm flux	Ap
21 Oct 2021	076	007
22 Oct 2021	077	008
23 Oct 2021	078	004

Bulletin

Solar activity was at very low levels. NOAA Active Region (AR) 2886 (Catania sunspot region 64) remained stable. The small region seen to emerge yesterday in the north-eastern quadrant (Catania sunspot region 65) has developed further spots but has not produced any significant flaring activity. A new region is expected to rate onto the solar disk over the next 24 hours, from which some low B-level flares have already been recorded from beyond the limb. Solar activity is expected to be very low over the next 24 hours with a slight probability of C-class flares.

No Earth directed CMEs have been detected in the available coronagraph imagery.

The greater than 10 MeV proton flux was at nominal levels over the past 24 hours and is expected to remain so for the next 24 hours. The greater than 2 MeV electron flux remained below the 1000 pfu alert threshold and is expected to increase slightly but remain below this threshold during the next 24 hours. The 24h electron fluence was at nominal levels and is expected to remain so.

The expected High Speed Stream (HSS) has arrived. The solar wind speed (DSCOVR), which was 400 km/s at the start of the period, began to increase from 18UT reaching a maximal value of 560 km/s and remaining above 500 km/s for the rest of the period. The total magnetic field also increased and reached a maximum value of 12 nT at 21UT, before then decreasing and stabilizing around 5 nT. The Bz varied between -6 and +6 nT, but was mostly positive. The interplanetary magnetic field phi switched into the negative sector (directed towards from the Sun) from 14UT. The solar wind speed is expected to continue to be slightly enhanced on Oct 21 and 22, due to the influence of the HSS.

Geomagnetic conditions were at quiet levels (NOAA Kp and local K Dourbes recorded values of 1-2) over the past 24 hours. Geomagnetic conditions are expected to be quiet to unsettled on Oct 21 and Oct 22, with a slight possibility of an isolated active period in response to any extended periods of negative Bz.

Today's estimated international sunspot number (ISN): 016, based on 16 stations.

Solar indices for 20 Oct 2021

Wolf number Catania	022
10cm solar flux	076
AK Chambon La Forêt	010
AK Wingst	006
Estimated Ap	006
Estimated international sunspot number	011 - Based on 25 stations

Noticeable events summary

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

All times in UTC

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