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Documentation for subroutine REDUC3, an algorithm for the linear filtering of gridded magnetic data

Open-File Report 77-784

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Abstract

Subroutine REDUC3 transforms a total field anomaly h1(x,y) , measured on a horizontal and rectangular grid, into a new anomaly h2(x,y). This new anomaly is produced by the same source as h1(x,y) , but (1) is observed at a different elevation, (2) has a source with a different direction of magnetization, and/or (3) has a different direction of residual field. Case 1 is tantamount to upward or downward continuation. Cases 2 and 3 are 'reduction to the pole', if the new inclinations of both the magnetization and regional field are 90 degrees. REDUC3 is a filtering operation applied in the wave-number domain. It first Fourier transforms h1(x,y) , multiplies by the appropriate filter, and inverse Fourier transforms the result to obtain h2(x,y). No assumptions are required about the shape of the source or how the intensity of magnetization varies within it.

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Documentation for subroutine REDUC3, an algorithm for the linear filtering of gridded magnetic data
Series title:
Open-File Report
Series number:
77-784
Edition:
-
Year Published:
1977
Language:
ENGLISH
Publisher:
U.S. Geological Survey,
Description:
14, [12] leaves :ill. ;27 cm.; (25 p. - PGS)