Abstract
In this study, using one-minute definitive data published by a number of INTERMAGNET observatories, we apply a number of time- and frequency-domain techniques to characterise the global, natural geomagnetic signal and isolate the artificial noise at an individual observatory. With the aim of developing an analytical tool that can be used to identify observatory noise against the natural signal, we report on the suitability of these techniques to detect common observatory noise types.