Viewing archive of Sunday, 16 July 2023

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2023 Jul 16 1245 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Warning condition (activity levels expected to increase, but no numeric forecast given)

	10cm flux	Ap
16 Jul 2023	177	006
17 Jul 2023	175	005
18 Jul 2023	172	011

Solar Active Regions and flaring

Solar flaring activity over the past 24 hours remained at moderate levels with an impulsive M1.1-flare, start time 08:16 UTC, peak time 08:26 UTC, end time 08:30 UTC on July 16th. The flare was produced by NOAA AR 3372 (beta-gamma-delta), which together with NOAA AR 3363 (beta-gamma-delta) remain the two largest and most complex active regions on the visible solar disc responsible for most of the flaring activity over the past 24 hours. Another notable flaring activity was an impulsive C8.8 flare with peak time at 20:01 UTC on July 15th produced by NOAA AR 3363. The flare was accompanied by a partial halo coronal mass ejection and type IV radio burst, triggering increase in the energetic proton particle fluxes. Some low C-class flaring was produced by NOAA AR 3373 (beta) and NOAA AR 3374 (alpha). NOAA AR 3367 (beta) has now rotated behind the west limb. The remaining active regions were quiet and stable. The solar flaring activity is likely to remain at moderate levels over the coming days with low chances for isolated X-class flaring.

Coronal mass ejections

The faint partial halo coronal mass ejection (CME) observed in LASCO/C2 coronagraph imagery at 19:10 UTC on July 14th and related to an on-disc filament eruption and C8.8 flaring from plage region NOAA AR 3370 remains difficult to analyse due to lack of STEREO COR2 data and overlapping surrounding events. A glancing blow from it could arrive at Earth on July 18th. Another partial halo CME was observed in LASCO/C2 coronagraph data at 20:06 UTC on July 15th. The CME is related to a C8.8 flaring from NOAA AR 3363 (beta-gamma-delta). The CME was associated with a type IV radio burst and triggered a minor radiation storm between 06:05 UTC and 09:05 UTC on July 16th. The bulk of the CME is expected to miss Earth and a rather weak glancing blow could be expected late on July 18th. A full halo CME was detected in LASCO/C2 coronagraph data at 04:49 UTC on July 16th. This event is deemed back-sided with no expected impact at Earth. No other Earth-directed CMEs have been detected in the available coronagraph imagery.

Coronal holes

A narrow negative polarity coronal hole is currently residing on the central meridian, but appears too small and weak to produce any observed high speed stream at Earth.

Solar wind

Over the past 24 hours the solar wind parameters (ACE and DSCOVR) appear to have returned to background slow solar wind levels. There was no sign of the expected high speed stream arrival from a negative polarity coronal hole and it is no longer expected to arrive. The interplanetary magnetic field was stable with value around 7 nT. The Bz component was weak with minimum value of -5 nT. The orientation of the interplanetary magnetic field has been solely in the negative sector (directed towards the Sun). The solar wind density registered in both ACE and DSCOVR satellites has decreased to below 1 ppc making the estimations of the velocity and temperature currently untrustworthy. Background slow solar wind conditions are expected to continue throughout July 16th and July 17th with possible further enhancements on July 18th pending anticipated possible high speed stream and mixed glancing blow arrivals.

Geomagnetism

The geomagnetic conditions over the past 24 hours were quiet to unsettled. Mostly quiet geomagnetic conditions with isolated unsettled periods are expected over the next two days before possible weak high speed stream and glancing blow arrivals on July 18th.

Proton flux levels

Over the past 24 hours the greater than 10 MeV GOES proton flux levels registered a minor radiation storm between 06:05 UTC and 09:05 UTC on July 16th. The radiation storm was related to the partial halo CME observed in the coronagraph imagery at 20:06 UTC on July 15th and accompanied by a type IV radio burst. The greater than 10 MeV proton flux levels are now decreasing, currently below 3 pfu. The greater than 50 MeV proton flux has shown only slightly elevated levels and is currently back to background levels. The greater than 100 MeV proton flux levels remained at background levels throughout the event. The radiation storm was also registered in the energetic proton particle fluxes measured at STEREO. The greater than 10 MeV GOES proton flux is expected to decrease towards background levels, but further enhancements remain possible over the next days with the enhanced solar eruptive activity.

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux as measured by GOES 16 and GOES 18 was well below the 1000 pfu threshold. The greater than 2 MeV electron flux is expected to be below the 1000 pfu threshold in the upcoming days. The 24h electron fluence was at nominal levels and is expected to remain so over the next days.

Today's estimated international sunspot number (ISN): 160, based on 17 stations.

Solar indices for 15 Jul 2023

Wolf number Catania	///
10cm solar flux	179
AK Chambon La Forêt	012
AK Wingst	008
Estimated Ap	009
Estimated international sunspot number	134 - Based on 21 stations

Noticeable events summary

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

All times in UTC

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