**4. Concluding remarks**

The goal of this chapter was to demonstrate applications of the Earth's gravity field in Geodesy and Global Geophysics. In Geodesy, the main goal is to determine the physical shape of the Earth, or the geoid, and its importance in levelling and height systems were discussed. Philosophies behind three well-known methods of geoid determination, such as Remove-Compute-Restore, Stokes-Helmert and Leastsquares modification of the Stokes formula with additive corrections, were discussed.

When the temporal variation of the gravity field is disregarded and the field is considered static, some geophysical subjects can be studies by them to understand the Earth's interior such as the crustal structure, density contrast between the crust and mantle, sediment basement, ice thickness, and depth of ocean water determination. In addition, the sub-lithospheric stress induced by mantle convection and its propagation through the lithosphere can also be determined using gravity data.

By studying the temporal variations of the gravity field, Geodynamic phenomena can be studies. Post-glacial rebound, determining the land uplift rate and mantle viscosity, studying the earthquakes and their epicentre and also ground water storage mapping are the subject which can be studied by these variations.

One distinction between the application of the gravity field in Geodesy and global geophysics is the resolution of gravity field. The main purpose of Geodesy is to determine the shape of the Earth as precise and accurate as possible, and focus is on recovering the high frequencies of the gravity field, by combining satellite and terrestrial data with mathematical tools with the least approximations. However, in Geophysics due to lack our knowledge about the Earth's interior structure and dynamic, different assumptions have be made and also the mathematical models are developed based on them. In addition high resolution gravity data do not play a significant role in global Geophysics.

**Author details**

University West, Trollhättan, Sweden

provided the original work is properly cited.

\*Address all correspondence to: mehdi.eshagh@hv.se

*The Earth's Gravity Field Role in Geodesy and Large-Scale Geophysics*

*DOI: http://dx.doi.org/10.5772/intechopen.97459*

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

Mehdi Eshagh

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