Viewing archive of Sunday, 25 July 2021

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2021 Jul 25 1238 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
25 Jul 2021	084	009
26 Jul 2021	082	004
27 Jul 2021	080	019

Bulletin

Solar activity was at very low levels over the past 24 hours. There are currently three active regions remaining on the visible solar disc. Catania sunspot group 21/NOAA 2848 has decayed into a plage. Catania sunspot group 24/NOAA 2849 and Catania sunspot group 23/NOAA 2847 have remained stable and magnetically simple. Catania sunspot group 22/NOAA 2846 remained inactive with magnetic type beta. The X-ray flaring activity for the next 24 hours is expected to be at very low to low levels with a decreasing probability for C-class flaring.

No Earth-directed coronal mass ejections (CMEs) were detected in the available coronagraph imagery. A glancing blow from the eastward CME driven by the C4.3 flare on July 24th has a very low chance of arrival to Earth during the night of July 28th.

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 remained under the 1000 pfu threshold and is expected to remain so. The 24h electron fluence was at nominal levels and is expected to remain in the next 24 hours.

Over the past 24 hours the solar wind activity (ACE and DSCOVR) was low. The solar wind speed was on average below 350 km/s with some short-lived enhancements up to 470km/s possibly due to the faint patchy coronal hole (CH) pattern reported around the central meridian several days ago. The total magnetic field remained weak in the range of 2.3 to 6.3 nT. The north-south (Bz) component was very weak with values between -4.1 to +3.4 nT. The interplanetary magnetic field remained in the positive sector directed away from the Sun.

The geomagnetic conditions over the past 24 hours were globally quiet with a single isolated locally unsettled period as registered by K Dourbes. Mostly quiet geomagnetic conditions are expected for the next 24 hours with the possibility for isolated unsettled periods. The mid-latitude extension of the positive polarity northern polar CH, reported to cross the central meridian on July 24th, has now merged with a small low-latitude positive polarity CH and continues to partially reside on the central meridian. The HSS originating from these CHs is expected to arrive early on July 27th and persist for several days. Unsettled to active geomagnetic conditions are expected for this period with a possibility for a minor geomagnetic storm on July 27th and July 28th.

Today's estimated international sunspot number (ISN): 031, based on 21 stations.

Solar indices for 24 Jul 2021

Wolf number Catania	///
10cm solar flux	084
AK Chambon La Forêt	008
AK Wingst	004
Estimated Ap	004
Estimated international sunspot number	027 - Based on 23 stations

Noticeable events summary

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

All times in UTC

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