INTEGRATION OF AEROMAGNETIC DATA ACQUIRED AT DIFFERENT TIMES WITH VARYING ELEVATIONS AND LINE SPACINGS

The methods required for integrating magnetic data sets from surveys flown with contrasting specifications at different times are described. The first requirement in the process of integration is to bring the data sets obtained at different elevations to the same reference level. Various methods are available to continue magnetic fields from one horizontal plane to another. The procedure for continuation of the magnetic held from a draped surface to a constant barometric level requires an equivalent source representation of the field at all points of observation. Data sets continued to the same elevation over adjacent areas are found to exhibit mismatch along the area boundaries. The mismatch between data values along profiles running across a boundary can be explained by changes in level. gradient. and curvature of the fields in the two data sets in the neighborhood of the boundary. The method discussed for making the two fields compatible depends, basically, upon the adjustment of quadratic surfaces representing the fields on both sides of a boundary. Examples are also provided to demonstrate the usefulness of these methods in the preparation of an integrated data set at a reference level using data sets flown at different elevations above the ground surface in the state of Nevada.