Solar alert

Issued on 2023 Mar 24 0818 UTC

A severe geomagnetic storm (G4) was registered with NOAA Kp reaching 7.7 in the time interval 03:00 to 06:00 UTC on March 24th. The severe storm was triggered by highly disturbed solar wind conditions due to an ICME arrival. Most likely candidate is the partial halo CME related to a C4.4-class flaring and consequent filament eruption in the north-east quadrant near NOAA AR 3258 on March 20th. The severe storm was preceded by two major storms with NOAA Kp reaching 6.6 and 7.3 and moderate storm before. Locally in Belgium only minor and moderate storm levels were reached. Since early UTC evening on March 23rd the interplanetary geomagnetic field registered long periods with magnitude of approximately 20 nT and steady north-south Bz component with value close to -16 nT. The solar wind speed has declined over night with current value around 410 km/s. The interplanetary magnetic field has declined to 10 nT at present with positive Bz at the time of writing as the passage of the magnetic cloud related to the ICME arrival is gradually coming to an end. Further moderate or minor storms remain possible until the end of the ICME and more can be expected with the anticipated arrival of a high speed stream and a possible glancing blow later on March 24th.

Reference for this alert

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