Viewing archive of Monday, 10 April 2023

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2023 Apr 10 1232 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Active conditions expected (A>=20 or K=4)

Solar protons

Quiet

	10cm flux	Ap
10 Apr 2023	146	018
11 Apr 2023	146	015
12 Apr 2023	146	010

Bulletin

Over the past 24 hours, the solar flaring activity has been at low levels with 22 C-class flares reported. The majority of the flares originated from the Catania sunspot group 50 (NOAA AR 3272), which still has a beta-gamma configuration of its photospheric magnetic field. Furthermore, a region that is located at the South-East solar limb, which has yet to rotate onto the visible side of the solar disk was reported to have produced the strongest flare, a GOES C6.0 flare, with peak time at 04:39 on April 10. For the next 24 hours, we expect C-class flares and possibly also isolated M-class flares.

Over the past 24 hours, a south-directed CME was observed in the evening of April 9, for the first time seen in the SOHO/LASCO C2 field of view at 19:48 UT. This CME not expected to reach Earth, but a glancing blow is possible.

The greater than 10MeV proton flux was at nominal levels over the past 24 hours and is expected to remain so. The greater than 2MeV electron flux has been above the threshold from 12:45 UT until 19:50 UT on April 9. Since then, it is at background levels. We expect the 2MeV electron flux to increase again over the next 24 hours due to enhanced solar wind conditions.. The 24h electron fluence was at moderate levels over the past 24 hours and we expect it to decrease to normal levels over the next 24 hours.

Over the past 24 hours the solar wind speed has stayed almost constant with values of about 350 km/s. Around 22:00UT a forward shock wave has been observed in the in situ data with interplanetary magnetic field (IMF) values up to 13 nT. The shock wave was followed by the arrival of the interplanetary coronal mass ejection. The present value of the IMF is 10 nT and the solar wind speed is about 500 km/s. The solar source of this ICME is not completely clear. One possibility is a faint, wide CME observed first time in the SOHO/LASCO C2 field of view at 09:24 UT on April 06, above the East solar limb. The other possibility is that the source is a stealth CME with no clear on-disc signatures. We expect the arrival of fast solar wind at Earth starting from the morning of April 11. The expected fast wind is associated with a small coronal hole that crossed the central meridian on April 8.

During the last 24 hours, the geomagnetic conditions were mostly unsettled. A short interval of active conditions was reported by local station at Dourbes from 08:00 UT until 10:00 UT on April 10 (K was between 2 and 4). The Kp-index as reported by NOAA remained at values between 3 and 4-. Geomagnetic conditions are expected to stay unsettled for the next 24 hours.

Today's estimated international sunspot number (ISN): 091, based on 11 stations.

Solar indices for 09 Apr 2023

Wolf number Catania	///
10cm solar flux	140
AK Chambon La Forêt	015
AK Wingst	007
Estimated Ap	006
Estimated international sunspot number	060 - Based on 25 stations

Noticeable events summary

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

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