Magnetometer array studies in Finland - determination of single station transfer functions

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K. Pajunpaa

Abstract

In 1981 and 1982 four arrays of 30 or 31 magnetometers were operated on the Baltic Shield in central and south-eastern Finland to measure the natural magnetic field variations. These measurements were used to deduce some information about the lateral variation of the electrical conductivity within the Earth's crust. The stations were situated between latitudes 56° and 64° geomagnetic north. As substorms often extend over this area, most magnetic disturbance events have strong external spatial gradients and are not suitable for determining the electrical conductivity distribution inside the Earth. Some magnetic disturbance events with only smooth external spatial gradients could be selected and used for further analysis. For 11 of these events (2–6 h long), the horizontal spatial wavenumber k has been calculated. The product of the wavenumber k and the inductive scale length C was then used as an acceptance criterion and as a weighting function in the calculation of single station transfer functions. Most of the data were not acceptable for the criterion k · |C| < 0.3 for periods longer than 500 s. Because of the small number of acceptable data the statistical significance was not sufficient for all sites. Despite these problems induction vectors and conducted hypothetical vertical field maps could be used to locate conductivity anomalies. Intensive induction was found in three zones in the area under investigation.


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How to Cite
Pajunpaa, K. 1984. “Magnetometer Array Studies in Finland - Determination of Single Station Transfer Functions”. Journal of Geophysics 55 (1), 153-60. https://journal.geophysicsjournal.com/JofG/article/view/223.
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References

Bailey, R.C., Edwards, R.N., Garland, G.D., Kurtz, R., Pitcher, D. (1974) Electrical conductivity studies over a tectonically active area in eastern Canada. J. Geomagn. Geoelectr. 26:125-146

Beamish, D. (1979) Source field effects of transfer functions at midlatitudes. Geophys. J. R. Astron. Soc. 58:117-134

Jones, A.G. (1977) Geomagnetic induction studies in southern Scotland. Ph.D. thesis, Dept. of Geophysics, Edinburgh, Univ. Edinburgh, Scotland

Jones, A.G. (1980) Geomagnetic induction studies in Scandinavia - I Determination of the inductive response function from the magnetometer array data. J. Geophys. 48:181-194

Jones, A.G. (1981) Geomagnetic induction studies in Svandinavia - II Geomagnetic depth sounding, induction vectors and coast effects. J. Geophys. 50:23-36

Jones, A.G., Olafsdottir, B., Tiikkainen, J. (1983) Geomagnetic induction studies in Scandinavia - Ill Magnetotelluric observations. J. Geophys. 54:35-50

Kuppers, F., Post, H. (1981) A second generation Gough-Reitzel magnetometer. J. Geomagn. Geoelectr. 33:225-237

Mersmann, U., Baumjohann, W., Kuppers, F., Lange, K. (1979) Analysis of an eastward electrojet by means of upward continuation of ground-based magnetometer data. J. Geophys. 45:281-298

Pajunpaa, K., Heikka, J., Korja, T. (1983) Magnetometer array studies in Finland. J. Geomagn. Geoelectr. (In press)

Porath, H., Oldenburg, D.W., Gough, D.I. (1970) Separation of magnetic variation fields and conductive structures in the western United States. Geophys. J.R. Astron. Soc. 19:237-260

Rokityansky, I.I., Yasin, N.D., Golod, M.I., Novicky, G.P., Rokityanskaya, D.A., Sokolov, S.Ya. (1979) Electric conductivity anomalies in S-Karelia. Geofz. Akad. Nauk USSR, 89:36-39 (In Russian)

Schmucker, U. (1970) Anomalies of geomagnetic variations in the south-western United States. Bull. Scripps Inst. Oceanogr., La Jolla, Calif. 13, 165 pp.

Schmucker, U. (1973) Regional induction studies: a review of methods and results. Phys. Earth Planet. Inter. 7:365-378

Woods, D.V., Lilley, F.E.M. (1979) Geomagnetic induction in central Australia. J. Geomagn. Geoelectr. 31:449-458

Zhang, P., Rasmussen, T., Korja, T., Koivukoski, K. (1983) Preliminary results from a MT study of a conductive zone in Finland. Paper presented at the symposium on the geoelectric model of the Baltic Shield, Oulu, Nov. 15-18