I am trying to understand some plots of the earth's magnetic variation (declination) by trying to correlate what I see in a figure like the one below with the variation reported for some airports. I'm particularly interested in those locations where the figure seems to show an extreme variation of up to 90 degrees. But when I look up nearby airports, I don't see any variations values outside of 22 degrees.
Some locations I have checked are
- SOG, Sorong, Indonesia (1.47 degrees)
- BWN, Brunei (0.13 degrees)
- CMB, Bandaranaike International Airport , Sri Lanka (2.15 degrees)
- REC, Recife, Brazil (22.12 degrees)
- IVA, Ambanja, Madagascar (9.8 degrees)
Am I misreading the figure? What are some airports with very large magnetic variations? I'd like to compare them with this figure and try to understand what I am missing.