Normal Gravity

Definition

Normal Gravity :

The gravity induced by an ellipsoid of revolution which approximates the figure of the real Earth.

Introduction

The Earth’s gravity field expresses the result of applying Newton’s gravitational law to the entire dynamic Earth system. For a point situated on the Earth’s surface, the gravitational attraction would be given as the sum of every individual attracting force applied to that point from the underlying elementary mass distributions, whose position and density vary through the Earth’s interior. When one adds the Earth’s rotational motion to this attraction component, the fundamental expression for the gravity vector is obtained as (Heiskanen and Moritz 1967)

$$ \textbf{g}=\nabla \left(\textrm{V}+\Phi \right) $$

(1)

where V the gravitational and Φ the centrifugal potential functions. Substituting their corresponding definitions we get

$$ {\displaystyle \begin{array}{rcl}\textbf{g}& =& g\...