Positive polarity coronal hole high speed solar stream sparks G2 – Moderate geomagnetic storming

Earth is under the influence of a positive polarity coronal hole high speed solar stream (CH HSS), triggering G2 – Moderate geomagnetic storming.

In 24 hours to 12:30 UTC on August 8, solar wind parameters indicated the onset of a positive polarity CH HSS.¹

Total field reached a peak of 14 nT, the Bz component was primarily southward reaching up to -13 nT, while solar wind speeds increased from ~420 km/s to ~565 km/s during the period. Phi was predominantly positive.

Geomagnetic K-index of 5 (G1 – Minor geomagnetic storm) threshold was reached at 22:22 UTC on August 7 and K-index of 6 (G2 – Moderate geomagnetic storm) at 23:59 UTC.

G2 – Moderate geomagnetic storm potential impacts:

• Area of impact primarily poleward of 55 degrees Geomagnetic Latitude.
• Induced Currents – Power grid fluctuations can occur. High-latitude power systems may experience voltage alarms.
• Spacecraft – Satellite orientation irregularities may occur; increased drag on low Earth-orbit satellites is possible.
• Radio – HF (high frequency) radio propagation can fade at higher latitudes.
• Aurora – Aurora may be seen as low as New York to Wisconsin to Washington state.

Solar wind parameters are expected to continue under the influence of multiple positive polarity CH HSSs through August 10. Solar wind speeds in the 550 – 650 km/s range are likely through August 9 based on current trends and sporadic STEREO A Mag/PLASTIC data.

The geomagnetic field is likely to reach G1 – Minor geomagnetic storming levels again late on August 8. Otherwise, active conditions are expected.

Unsettled to active levels, with a chance for isolated G1 – Minor geomagnetic storming periods, are expected on August 9 and 10 due to an ongoing procession of positive polarity CH HSS.

Solar activity was at low levels over the past 24 hours and are expected to remain and very low to low activity, with a chance of C-class solar flares, thorugh August 10.

The greater than 2 MeV electron flux was at normal to moderate levels and the greater than 10 MeV proton flux maintained background values.

The greater than 2 MeV electron flux is expected to be at normal to moderate levels on August 8 followed by moderate to high levels on August 9 and 10. The greater than 10 MeV proton flux is expected to continue at background levels.

References:

¹ Forecast Discussion – Issued: 2022 Aug 08 1230 UTC – Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center

Featured image credit: NASA/SDO, LMSAL