Viewing archive of Sunday, 23 May 2021

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2021 May 23 1231 UTC

SIDC Forecast

Solar flares

M-class flares expected (probability >=50%)

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Quiet

	10cm flux	Ap
23 May 2021	076	007
24 May 2021	076	007
25 May 2021	076	012

Bulletin

NOAA AR 2824 (Catania 96) has grown significantly in complexity over the last 24 hours, it has now a beta-gamma magnetic field configuration and it has produced three M-class flares and numerous C-class flares. The strongest one was an M1.4 flare, peaking at 21:36 UT on 22 May. More M-class flares can be expected.

Three (partially) Earth directed CMEs erupted on 22 May. Two of them are associated with M-class flares. The first one starting at 09:12 UT (LASCO C2) with 300 km/s and about 90 degrees angular width, expected arrival at 23 UT on 26 May. The second one at 16:23 UT (COR2A), with a speed of 460 km/s and an expected arrival time at 02 UT on 26 May. The last one started at 22:00 UT (COR2A), with a speed of 629 km/s, and expected to arrive at 13 UT on 25 May. The last two were faint in LASCO and better visible in COR2. The speed of the CMEs increased from the first to the third, so they will encounter and interact on their way to the Earth, making accurate arrival time predictions difficult.

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 barely below the 1000 pfu in the past 24 hours, it is expected to decrease in the coming 24 hours. The 24-hour electron fluence was at normal levels in the past 24 hours, but close to the moderate limit, it may reach this level before decreasing in the coming 24 hours.

The solar wind speed at the Earth has been around 420 km/s over the past 24 hours, with interplanetary magnetic field magnitude around 3 nT. The polarity of the magnetic field was mostly negative (towards the Sun). Similar conditions are expected for the next 24 hours.

Geomagnetic conditions have been quiet (KDourbes 1-2, Kp 1-2), similar conditions can be expected for the next 24 hours.

Today's estimated international sunspot number (ISN): 026, based on 15 stations.

Solar indices for 22 May 2021

Wolf number Catania	///
10cm solar flux	076
AK Chambon La Forêt	010
AK Wingst	006
Estimated Ap	005
Estimated international sunspot number	017 - Based on 26 stations

Noticeable events summary

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

All times in UTC

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