Occupancy
In potential theory, surface occupancy is the theoretical or computational application of mass or charges to models of solids in order to consider or estimate the effect of small changes with simple means.
While in the numerical modeling of a body or force field an exact calculation of changes to the body or the field means a disproportionately large effort, the " condensation " of small mass or charge changes on fictitious (infinitely thin) layers can be solved theoretically easily.
Some uses
- Calculation of models of the earth's gravity field
- topographical reductions in gravity measurements
- Search for the cause of interference potentials , e.g. B. by heavy or magnetic rocks
- Disruptive influences on electrical or magnetic fields .
Three examples
In gravimetry and magneto-gravimetric exploration , e.g. B. the effect of additional or missing masses can be estimated by assuming a thin "interference layer", which receives a fictitious mass occupancy . The effect of a uniformly covered layer on the measuring point then corresponds to the solid angle at which the surface covering appears.
When determining geoid or potential models, a gravity disturbance - initially still undetected in its cause - can be localized by covering the earth's surface with a uniform grid of thin masses. Their masses or densities are set as unknown parameters and calculated by means of a mediating adjustment according to the smallest squares or by means of collocation . The subsequent interpretation is z. B. made in the form of different densities of the earth's crust .
A method based on this principle for the combined evaluation of gravity anomalies , geoid undulations , spherical function or earth models is the " potential of the simple layer " method developed by KR Koch . It was applied to gravity measurements and data from satellite altimetry in the 1970s and can reduce the computational effort to less than half compared to more stringent methods.