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A study of the EGM2008 model of Earth's gravitational field

Published online by Cambridge University Press:  29 September 2022

Don Koks Open the ORCID record for Don Koks [Opens in a new window]
Don Koks*
Affiliation:
Defence Science and Technology Group, P.O. Box 1500, Edinburgh, South Australia 5111, Australia
*
*Corresponding author. E-mail: [email protected]
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Abstract

The Earth Gravity Model 2008 (EGM2008) is now some years old, and yet information on how to use it to calculate Earth's gravity remains obscure outside the field of geodesy. We describe the mathematics necessary to implement EGM2008, and use this to discuss several points of the model: its sensitivity to the number of spherical harmonics being summed, nuances and a trap for physicists and mathematicians in the normalisation it uses, and a comparison with other work. We conclude that one must not overestimate the precision shown by a global-fit model such as EGM2008.

Keywords

EGM2008Earth gravityEarth potentialassociated Legendre functionsspherical harmonics
Type
Research Article
Information
The Journal of Navigation , Volume 75 , Issue 5 , September 2022 , pp. 1017 - 1034
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Copyright
Copyright © The Author(s), 2022. Published by Cambridge University Press on behalf of The Royal Institute of Navigation

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