Viewing archive of Thursday, 29 July 2021

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2021 Jul 29 1237 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
29 Jul 2021	079	008
30 Jul 2021	079	007
31 Jul 2021	080	007

Bulletin

The solar activity has been quiet over the past 24 hours, with the X-ray flux below C-level. A small bipolar sunspot groups (Catania sunspot group 25) is visible on the disc, no significant faring activity has been observed within this sunspot. The solar activity is expected to remain low levels over the next 24 hours.

Yesterday a large coronal dimming was observed from 08:03 UTC to 09:33 UTC on July 28 in the north-west quadrant. The associated coronal mass ejection was then observed on the SOHO/LASCO-C2 coronagraphe images on July 28 at 10:36. The projected speed was estimated around 400 km/s and the true speed around 520 km/s. The arrival time on Earth of the coronal mass ejection glancing blow is estimated on July 31 around 22:00 UTC (+/-12h). Only minor to no effect is expected on the solar wind conditions and geomagnetic activity from this CME.

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 was below the 1000 pfu threshold in the past 24 hours. The greater than 2 MeV electron flux may slightly increase during the next 24 hours due to the high-speed streams. The 24h electron fluence was at normal levels in the last 24 hours and may also slightly increase for the next 24 hours.

The solar wind parameters (as observed by ACE and DSCOVR) are enhanced due to the high-speed streams associated with the positive polarity northern polar coronal hole, that crossed the central meridian on July 24. The solar wind speed fluctuated around 510-515 km/s. The interplanetary magnetic field magnitude remained enhanced at the beginning of the period (up to 14 nT) then decreased to values below 7 nT. The Bz component mainly positive (with values between -6 nT and 14 nT) then returned to nominal values. The enhanced solar wind conditions are expected to persist for the next few days.

The geomagnetic conditions were unsettled in responses to the high-speed streams (NOAA-Kp and K-Dourbes = 3). The conditions are expected to be mainly quiet with possible short periods of unsettled conditions.

Today's estimated international sunspot number (ISN): 003, based on 25 stations.

Solar indices for 28 Jul 2021

Wolf number Catania	024
10cm solar flux	079
AK Chambon La Forêt	021
AK Wingst	018
Estimated Ap	017
Estimated international sunspot number	005 - 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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