Value chain · CLM-1380
In plain terms
NOAA's storm levels G1 to G5 correspond to the Kp disturbance index reaching 5, 6, 7, 8 and 9.
The claim as recorded
The NOAA Space Weather Scales define the geomagnetic storm classes by the 3-hourly Kp index: G1 at Kp=5, G2 at Kp=6, G3 at Kp=7, G4 at Kp=8 "including a 9-", and G5 at Kp=9. NOAA states that Kp is the basis "but other physical measures are also considered."
Evidence behind this: T3: an agency's published scale and table, not a peer-reviewed measurement.
Scope and limits
The scale is NOAA's own. It is a convention, not a physical threshold for ionospheric effects. The Explorer FB-02 mapping from G class to Ionosphere layer state is this site's choice; this record supports only the Kp-to-G step.
What it assumes
No assumptions are recorded against this claim.
Where it comes from
PDF p.1: physical measure "Kp values* determined every 3 hours"; G5 "Kp=9"; G4 "Kp=8, including a 9-"; G3 "Kp=7"; G2 "Kp=6"; G1 "Kp=5"; footnote "Based on this measure, but other physical measures are also considered." (the footnote is printed under each of the three scales; the one cited is the G-scale footnote).
Basis: planetary Kp index, determined every 3 hours
Related records
- Answers question
- QST-009 not published in this release
Cite this
energyaperture.com/c/clm-1380
CLM-1380, Energy Aperture, as of 2023-12-11.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-135
- 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...CLM-1381NOAA'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...