SRC-135

NOAA SWPC geomagnetic storm G-scale occurrence table

Commissioned by US NOAA. Who paid for a study is recorded because it bears on how its conclusions should be read, not because it makes them wrong.

Published claims resting on this source

• CLM-0118 (low confidence) Storms big enough to disturb the ionosphere over the UK happen on roughly 12 to 18 days a year on average, mostly around solar maximum. Which figure is right is not yet known.
• CLM-1380 NOAA's storm levels G1 to G5 correspond to the Kp disturbance index reaching 5, 6, 7, 8 and 9.
• CLM-1381 NOAA's own table confirms the storm-day counts the register was using: about 130 strong, 60 severe and 4 extreme storm days in an average 11-year cycle.

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