Analytical Downward and Upward Continuation Based on the Method of Domain Decomposition and Local Functions

Abstract

Upward and downward continuation of gravity anomalies are usually based on the Poisson integral and its iteration. By using the method of domain decomposition, a local function can be used for upward and downward continuation of gravity data. This approach decomposes the total area into small domains, and uses local functions to model the disturbing potential within each of these domains. One appropriate set of local functions, used in this paper, is the 3-D Fourier series. The results of the domain decomposition approach are compared to the Poisson integral for upward continuation in a flat area (to avoid large topographic effect) and downward continuation in a rough area in the Rocky Mountains. The data consist of ′×′ grid of NGS’ surface gravity over the conterminous US (CONUS). In addition, INTERMAP’s airborne gravity tracks in the Baltimore area are used to validate the upward continuation results of the two methods. The advantages and disadvantages of the local functions versus the Poisson integral approach are discussed