CME reaches Earth, sparking G1 – Minor geomagnetic storm

aurora forecast for 0512z july 23 2022

Coronal mass ejection (CME) produced by a long-duration C5.6 solar flare on July 21, 2022, hit Earth’s magnetic field at 02:59 UTC on July 23, 2022, sparking G1 – Minor geomagnetic storm.

Solar wind parameters continued under coronal hole high speed stream (CH HSS) influence through 02:29 UTC on July 23 when parameters became further enhanced due to the arrival of the anticipated July 21 CME.1

Prior to 02:29 UTC, solar wind speeds averaged about 535 km/s, total field ranged from 7-9 nT while the Bz component varied between +7/-4 nT.2

After 02:29 UTC, wind speeds briefly increased to 700 km/s before settling down to an average of 675 km/s. Total field increased to 10 – 15 nT while the Bz component ranged between +/-12 nT. Phi angle was predominantly negative in 24 hours to 12:30 UTC.

planetary-k-index 3 days to july 23 2022
aurora forecast for 0512z july 23 2022 bg

The geomagnetic field was at quiet to unsettled levels through 03:00 UTC under persistent negative polarity CH HSS influence. After 03:00 UTC, the field increased to active to minor storm levels (G1 – Minor) due to transient effects.

G1 – G2 (Minor – Moderate) geomagnetic storm levels are likely on July 23, with a chance for G3 – Strong due to CH HSS influence coupled with CME effects. Quiet to active levels are expected on July 24 and quiet to unsettled levels on July 25 as conditions slowly wane.


1 CME produced by long duration C5.6 solar flare expected to reach Earth early on July 23 – The Watchers – July 21, 2022

2 Forecast Discussion Issued: 2022 Jul 23 1230 UTC – Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center

Featured image credit: SWPC


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