Viewing archive of Thursday, 18 April 2024

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2024 Apr 18 1232 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Quiet

	10cm flux	Ap
18 Apr 2024	224	006
19 Apr 2024	228	017
20 Apr 2024	224	024

Solar Active Regions and flaring

Solar flaring activity was at moderate level, with multiple C-class flares and three M-class flares recorded in the past 24 hours. The largest flare of the period was an M2.2 flare, peaking at 02:32 UTC on Apr 18, associated with NOAA AR 3643 (beta class). This region also produced two further M-class flares (M1.6 and M1.3 peaking at 22:08 UTC on Apr 17 and 07:37 UTC on Apr 18, respectively). NOAA AR 3639 is currently the largest and most complex region on disk (Beta-Gamma- Delta), but produced only low level C-class flares. Low flaring activity was also produced by NOAA AR 3638 (beta class) and NOAA AR 3645 (beta-gamma class). NOAA AR 3633 and NOAA AR 3634 are expected to rotate over the west limb in the next day. 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) appears narrow and slow and is not expected to arrive to Earth. 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 CME can be seen in SOHO/LASCO-C2 from 02:36 on Apr 17. The CME is judged to be too narrow to reach Earth. Multiple CMEs, directed towards south-east from the Earth's perspective, were observed in SOHO/LASCO-C2 starting from approximately 17:16 on Apr 17, likely related to the flaring activity from NOAA AR 3638 and 3643. Further analysis is on-going to investigate if these CMEs have Earth directed components. No other Earth-directed CMEs have been detected in the available coronagraph imagery over the past 24 hours.

Coronal holes

A small negative polarity equatorial coronal hole has transited the central meridian today, on Apr 18.

Solar wind

Over the past 24 hours, the solar wind parameters reflected the waning influence of the ICME. The total magnetic field decreased from 10 nT to the values around 6 nT. The solar wind speed ranged between 360 km/s and 410 km/s. The southward component of the interplanetary magnetic field fluctuated between -7 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 solar wind conditions are expected to continue its return to the slow solar wind regime in the next 24 hours with a chance for weak enhancement on Apr 18 due to anticipated arrival of CME from Apr 15. On Apr 20 solar wind parameters might become 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 were quiet both globally and locally (NOAA-Kp and K-BEL: 1 to 2) during the last 24 hours. Geomagnetic conditions are expected to remain mostly at quiet to unsettled levels, with a chance of reaching active levels on Apr 18 due to possible CME arrival.

Proton flux levels

Over the past 24 hours the greater than 10 MeV GOES proton flux was at nominal levels and is expected to remain so with possible enhancements in case of increased levels of solar activity over the next days.

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): 217, based on 18 stations.

Solar indices for 17 Apr 2024

Wolf number Catania	251
10cm solar flux	217
AK Chambon La Forêt	008
AK Wingst	006
Estimated Ap	006
Estimated international sunspot number	208 - Based on 25 stations

Noticeable events summary

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

All times in UTC

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