Viewing archive of Wednesday, 17 April 2024

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2024 Apr 17 1231 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

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

Solar protons

Quiet

	10cm flux	Ap
17 Apr 2024	203	019
18 Apr 2024	209	041
19 Apr 2024	209	022

Solar Active Regions and flaring

Solar flaring activity was at moderate level, with multiple C-class flares and one M-class flare recorded in the past 24 hours. The largest flare of the period was an M1.1 flare, peaking at 18:02 UTC on Apr 16, associated with NOAA AR 3645. NOAA AR 3639, that has grown in size and became magnetically more complex (from beta-gamma to beta-gamma-delta) was the main driver of the flaring activity observed over the past 24 hours together with NOAA AR 3637 (beta-delta), NOAA AR 3641 (beta) and NOAA AR 3643 (beta-gamma). Other regions on the disc have simple configuration of their photospheric magnetic field (alpha and beta) and did not show any significant flaring activity. The solar flaring activity is expected to be at moderate levels over the next 24 hours, with M-class flares possible and a chance for X- class flare.

Coronal mass ejections

A small filament eruption occurred in the southeastern quadrant from around 18:36 UTC on Apr 16. The associated coronal mass ejection (CME) was observed in SoHO/LASCO C2 coronagraph data from 20:36 UTC onwards. The CME is directed primarily to the South from the Earth's perspective, analysis is ongoing to determine if there is an Earth- directed component. Another filament eruption was observed in the northern quadrant, first seen in SDO/AIA 304 at around 01:16 UTC on Apr 17. An associated faint CME can be seen in SOHO/LASCO-C2, however we are awaiting corresponding coronagraph data for further analysis. No other Earth-directed CMEs have been detected in the available coronagraph imagery over the past 24 hours.

Coronal holes

Small negative polarity equatorial coronal hole has began to cross the central meridian today, on April 17.

Solar wind

Over the past 24 hours, the solar wind parameters were slightly disturbed under the ICME influence. The total magnetic field reached 13 nT at 13:00 UTC on April 16, later decreasing to the values around 9 nT. The solar wind speed ranged between 350 km/s and 400 km/s. The southward component of the interplanetary magnetic field fluctuated between -12 nT and 8 nT. The interplanetary magnetic field phi angle varied between being directed towards the Sun to being directed away from the Sun. The effects of the CME are expected to slowly wane in the next 24 hours, further weak enhancement is possible from late on Apr 17- early on Apr 18 due to anticipated arrival of CME from Apr 15. On Apr 20 solar wind parameters might be slightly elevated due to the arrival of a high-speed stream from a negative polarity coronal hole, that started to cross the central meridian on Apr 17.

Geomagnetism

Geomagnetic conditions reached minor storm levels (NOAA-Kp = 5, K-Bel = 5) between 18:00 and 00:00 UTC on Apr 16. Conditions then reduced to quiet to unsettled levels. The minor storm period was reached due to the prolonged period of negative Bz. Predominantly unsettled to active geomagnetic conditions are expected for the next 24 hours with further intervals of minor or moderate storm conditions possible, due to the anticipated arrival of CME late on Apr 17 - early on Apr 18.

Proton flux levels

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.

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux, as measured by the GOES-16 satellite, remained below the 1000 pfu threshold. It is expected to remain below the threshold during the next 24 hours. The 24 hour electron fluence was at normal levels and is expected to remain at these levels for the following 24 hours.

Today's estimated international sunspot number (ISN): 204, based on 16 stations.

Solar indices for 16 Apr 2024

Wolf number Catania	///
10cm solar flux	199
AK Chambon La Forêt	039
AK Wingst	030
Estimated Ap	033
Estimated international sunspot number	181 - Based on 18 stations

Noticeable events summary

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

All times in UTC

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