The coronal mass ejection from the 6th September, associated with the X9.3 solar flare, arrived earlier than expected, overnight on 7th/8th September. The impact on the Earth's magnetosphere was recorded at BGS's magnetic observatories. The magnetic field began to strengthen from 23:00 UT (00:00 BST). Geomagnetic activity was high. Globally this reached a peak of Kp=8 STORM G4 levels which sustained for around 6 hours.
In the UK geomagnetic activity was greatest at our most northern observatory in Lerwick, Shetland Isles. The local K reached K=9, STORM G5 levels, which is the highest value in this activity scale. The field also varied rapidly - at one point the compass direction (declination) swung by more than 3 degrees in 2 minutes!
The auroral oval broadened and stretched southwards and aurora sightings have been reported across Scotland. Many areas were affected by cloud but those on the east coast were fortunate to find the clouds cleared in time for a spectacular show.
Although the initial impact has now passed, the solar wind remains elevated and energised so there will continue to be some chance of further auroral displays over the weekend depending on the nature of the solar wind (impossible to predict!).
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