Measurements and analysis of fluctuations in the Earths magnetic field in a coastal water area - originally presented at Marelec 97, June 1997

Forsvarets forskningsinstitutt accomplished in September 1991 a pilot study investigating fluctuations in the earth's magnetic field in a coastal water area in Norway. The experimental data was collected during seven days using four bottom-mounted three-axial fluxgate magnetometers sampled at 2 Hz and the paper describes the experiment and some of the results found. The long-time series are analysed with respect to power spectral density, squared coherence and phase shifts/time delays. A subtraction filter is introduced to reduce the ambient noise. The results are compared with results from other, equivalent measurements of fluctuations in the geomagnetic field. This report was originally presented as a paper at the conference Marelec'97 in London, June 1997.