A two-dimensional magnetometer array for ground-based observations of auroral zone electric currents during the International Magnetospheric Study (IMS)

Abstract

A two-dimensional magnetometer array was progressively installed in Scandinavia, from 1974 onwards, for operation during the IMS period (1977-1979). The 36 instruments, which are buried in the ground, are of the Gough-Reitzel type, i.e., classical magnetometers, with wire-suspended magnets and optical recording. The time-variation period range observable is from about 50 s to several days. In northern Scandinavia, the spacing between the stations is about 100-150 km in both the north-south and east-west directions. For presentation and analysis of the data a special Cartesian coordinate system has been introduced (the 'Kiruna system'). It is derived by mapping the local Earth's surface onto a tangential plane, with its origin close to Kiruna (geographic coordinates 67.8 N, 20.5 E). First results from some stations show that internal contributions to the recorded horizontal geomagnetic variations are small and possibly negligible at lower frequencies. However, at frequencies above about 2 mHz the variations of the vertical component display a strong amplification near the coast, and indicate the existence of conductivity anomalies at some inland locations. In order to demonstrate the observational capabilities of the array, equivalent overhead current configurations are presented which characterize a substorm recorded on October 7, 1976.

          ARK: https://n2t.net/ark:/88439/y001456

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