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I have looked around a bit, but haven't found a simple answer. At an altitude between 100-1000 km,
Is the magnetic field B still around $\sim 10^{-5}\ T$? Is there a simple equation that would provide an quick order of magnitude estimation?

Christopher Akritidis
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2 Answers2

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For future reference, if you even have only the most basic understanding of the physics behind it, you can guess that the fastest the mag field would drop off would be order $1\over r^2$ (which is a safe assumption usually. For Earth's case, it turns out to be $1\over r^3$). And you can guess that it originates from the center of Earth. Since we're sitting pretty at ~6371km, adding another 100-1000 km would not even decrease it by half, let alone an order of magnitude.

Jim
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You can use this link http://www.ngdc.noaa.gov/geomag-web/#igrfwmm for a quick estimation. Just give the latitude, longitude, and elevation.

At $0^o$ N and $0^o$ W and 1000km elevation the field is about 17,457.1 nT, so yes it is still around $\sim 10^{-5}\ T$

Andrew
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