Living Reference Work Entry

Encyclopedia of Geodesy

pp 1-10

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Disturbing Potential from Deflections of the Vertical: From Globally Reflected Surface Gradient Equation to Locally Oriented Multiscale Modeling Multiscale modeling

  • Willi FreedenAffiliated withGeomathematics Group, University of Kaiserslautern Email author 
  • , Christian GerhardsAffiliated withComputational Science Center, University of Vienna
  • , Helga NutzAffiliated withGeomathematics Group, University of Kaiserslautern
  • , Michael SchreinerAffiliated withInstitute for Computational Engineering ICE, University of Buchs

Definition

Deflection of the Vertical

Difference between the direction of the normal vector associated with the reference potential and the normal vector associated with the (actual) gravity potential.

Disturbing Potential

Difference between the normal potential and the true (measured) potential.

Introduction

The force of gravity, i.e., the resultant of gravitational and centrifugal force, provides a directional structure to the space above the Earth’s surface. It is tangential to the vertical plumb lines and perpendicular to all (level) equipotential surfaces. Any water surface at rest is part of a level surface. Level (equipotential) surfaces are ideal reference surfaces, for example, for heights. The geoid is defined as that level surface of the gravity field which best fits the mean sea level. Gravity vectors can be measured by absolute or relative gravimeters. The highest accuracy relative gravity measurements are ...

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