How does the Earth's magnetic field vary by altitude?

Asked by timtrueman (5765

) October 28th, 2010

I’ve got a three-axis magnetometer and I read in the magnetic field strength in nanoTesla units in the x, y and z axis. I’m fully aware of magnetic declination (and compensate for it). I’m wondering how might the magnetic field vary by altitude?

All I’ve found is this: http://www.ngdc.noaa.gov/geomag/magfield.shtml

It seems to have the data but I’m looking for a general description of how it changes at a high level and access to the raw data so I can dynamically compute the values onboard an aircraft without an internet connection.

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1 Answer

That’s a great question. While I don’t have an answer for certain, I would guess that based on the shape of magnetic flux lines forming a sort of figure-eightish, elliptical pattern, that the intensity of the field isn’t the same at the same altitude around the planet. In other words, if you went 50,000 feet above the equator it may be a weaker field than 50,000 feet above one of the poles.

Sorry to not have a real answer and just offer conjecture. I hope someone answers this accurately.

cockswain (15276

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