Value chain · CLM-0400
In plain terms
Millstone Hill sits at almost exactly the UK's magnetic dip angle, and the UK's modelled density range fits entirely inside what Millstone Hill measured. So Millstone Hill data can be used for the UK without extrapolating across latitude, though it is not a UK measurement.
The claim as recorded
The Millstone Hill radar site is a close magnetic analogue of the intended UK latitude, its IGRF-14 dip angle at 250 km being 66.49 degrees against 67.00 degrees for a UK site at 52.5 N 1.5 W, a difference of 0.51 degrees, whereas Sondrestrom is 79.38 degrees; and the modelled UK electron density range at 250 km of 1.29e10 to 1.55e12 per cubic metre falls entirely inside the Millstone Hill measured range of 2.32e9 to 7.30e12.
Scope and limits
A magnetic-geometry and density-range match is not a full climatological match. It removes the need to extrapolate across latitude, which was the stated blocker, but does not make Millstone Hill a UK measurement.
What it assumes
that dip angle and density range are the two properties that need to match for the joint Ne-Te distribution to transfer; other differences such as longitude sector and geomagnetic activity climatology are not controlled for
Where it comes from
This is the project's own working, shown in full:
IGRF-14 via ppigrf 2.1.0 at epoch 2026.5, 250 km, re-derived independently of the producing agent and agreeing to 0.01 degrees at all four sites: UK 67.00, Chilton 66.27, Millstone Hill 66.49, Sondrestrom 79.38. UK density range from SRC-121, PyIRI 0.1.7 at 250 km across three seasons, noon and midnight, solar min and max.
Related records
- Answers question
- QST-009 not published in this release
- Supersedes
- CLM-0097 not published in this release
Cite this
energyaperture.com/c/clm-0400
CLM-0400, Energy Aperture, as of 2026-09.
Connected records
Other published records linked to this one. A list, not a judgement.