Earth Model Selection for Computer Simulations
Abstract
Many scientific problems require the use of appropriate Earth models. This report presents a method of selecting from a variety of these models on the basis of range and bearing errors and CPU timing considerations that are incurred by each. The report begins by examining two types of Flat models and determines the better of the two. The reference for the determinations of all errors is the DoD standard Earth model representation, the World Geodetic System (WGS-84) reference ellipsoid. The report shows that for short distances a 'Midpoint Flat Earth' model is adequate at low latitudes. However, for longer ranges, better Earth models must be employed. The model proceeds to compare five spherical Earth models (different radii based on different assumptions). A model referred to as the 'Spherical Approximation' is shown to be a superior representation that allows for an increase in the permissible distance coverage under various constraining error budgets. For an error budget of 1000 m, the representation can be used to compute distances up to 250 nmi in the midlatitudinal region of 40 deg N to 70 deg N. For distances beyond 250 nmi, only a WGS-84 reference ellipsoid representation is adequate for the 1000-m error budget. (jhd)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 15, 1989
- Accession Number
- ADA216843
Entities
People
- J. J. Pich
- S. S. Leroy
Organizations
- United States Naval Research Laboratory