Optimal processing of satellite-derived magnetic anomaly data

It is shown how the concept of the power spectrum can be extended to two-dimensional spatial power spectra and how it can be used in determining optimal data processing methods for satellite-derived magnetic anomaly data and planning missions to obtain such data. The analysis techniques are applied to the data set and data-processing procedure described by Mayhew et al. (1980), a study that treats magnetic anomaly data for Australia and the surrounding ocean obtained by the polar orbit POGO series satellites. It is shown that the data-processing method used by Mayhew et al. is approximately equivalent to an invariant two-dimensional linear filter and that it is reasonably close to optimal with respect to accuracy, although some possible improvements are suggested. However, as is usual when filtering data, some real 'signal' is unavoidably removed along with the 'noise' resulting in errors that can be quite large. A method for reducing these errors by using additional data from a medium inclination orbit satellite (for example, 60 deg inclination) is proposed.