Aeromagnetic Gradiometry And Compensation

Although the concepts of aeromagnetic gradiometry are not new, it is only in the past several years, with a handful of gradient-equipped aircraft becoming operational, that the benefits are being realized. The main applications to date are the following:<br>• In a total field survey, a lateral gradiometer provides additional information about the field between the lines, leading to higher resolution surveys for a given line spacing, or conversely,<br>the equivalent resolution can be obtained with wider line spacing.<br>• The lateral gradiometer signal is free from diurnal variations and combined with a longitudinal gradient signal, van be used to calculate a total field that is largely diurnal free, thus leading to the possibility of fewer tie lines being needed for levelling.<br>• Using measured lateral and longitudinal gradient, a single profile can identify 2-D structures at strike angles other than perpendicular to the flight track, and for such structures, their depth van be accurately calculated using methods such as Werner deconvolution. This technique can be useful in the early redesign or reorientation of a survey with very little flown data.