Induction arrows from offshore floating magnetometers using land referencedata

Induction arrows are a traditional output of magnetovariational experiments , and represent transfer functions used quantitatively in the inversion of geomagnetic depth sounding data to give Earth electrical conductivity struc ture. In this paper, a technique is tested in which 'total-field' variation s are combined with horizontal-field data recorded simultaneously at remote stations in order to derive induction arrows. The method is first demonstr ated using total-field data recorded on land by an aeromagnetic base statio n, and then applied to data obtained from magnetometers floated offshore on the sea surface. The floating magnetometers were deployed in two configura tions: one tethered to the seafloor; the second free-floating.