Geomagnetic micropulsations: implications for high resolution aeromagnetic surveys

Abstract

The noise budget of an aeromagnetic survey is inherently high, having contributions from several components, for example, instrumentation, the platform, aircraft motion, navigation errors and effects of the temporal variations of the geomagnetic field. Variations in the geomagnetic time series are studied in terms of their contribution to the noise budget of high-sensitivity, high-spatial resolution aeromagnetic surveys. We quantify the electromagnetic and magnetic induction effect and show, from first order approximations, that these are insignificant. An experiment was undertaken to test the spatial coherence of the time varying component of the geomagnetic field. Over a baseline of 17 km, and during quiet magnetic conditions, the temporal variations are incoherent within the micropulsation band. This latter result suggests that the limiting factor in resolving the temporal constituent of the noise budget of an aeromagnetic survey is the spatial coherence of micropulsations.