Joint magnetometer array and radar backscatter observations of auroral currents in Northern Scandinavia

Abstract

As a contribution to the International Magnetospheric Study the University of Munster has installed an array of 32 Gough-Reitzel type magnetometers located mostly in Northern Scandinavia. Also for the IMS, the Max Planck Institute for Aeronomy at Lindau is operating the Scandinavian Twin Auroral Radar Experiment (STARE) which consists of two nearly identical backscatter radars located near Trondheim (Norway) and Sauvamaki (Finland). For a weak isolated substorm on October 7, 1976 the spatial structure of the electron density irregularities observed by the Trondheim-radar and the equivalent current distribution derived from the magnetic measurements have been compared. A good correspondence has been found between the location and magnitude of the maxima of the horizontal magnetic disturbance and the radar backscatter amplitude for an eastward electrojet. For most of the comparison there appeared also to be good agreement between the direction of the equivalent current and the direction antiparallel to the line-of-sight irregularity drift. This supports the idea that the backscatter irregularities are caused by current driven plasma instabilities and that it is possible to determine auroral ionospheric currents with the backscatter radar technique. However, during periods of enhanced electron precipitation, differences between the drift directions given by the two methods were observed.

          ARK: https://n2t.net/ark:/88439/y099827

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