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GEOPHYSICAL RESEARCH LETTERS, VOL. 34, L16101, doi:10.1029/2007GL030175, 2007

On the cause of IMF By related mid- and low latitude magnetic disturbances

S. Vennerstrom

Danish National Space Center, Technical University of Denmark, Copenhagen, Denmark


F. Christiansen

Danish National Space Center, Technical University of Denmark, Copenhagen, Denmark


N. Olsen

Danish National Space Center, Technical University of Denmark, Copenhagen, Denmark


T. Moretto

Geosciences Directorate, National Science Foundation, Washington, D.C., USA


Abstract

An analysis of the effect of the IMF B y on near-Earth low and mid-latitude magnetic disturbances is presented. In particular the contribution from field-aligned currents (FACs) connected to the polar regions is investigated. Based on statistically determined high-latitude FAC patterns for various Interplanetary Magnetic Field (IMF) directions, we estimate the FAC contribution to the mid- and low latitude magnetic disturbance and its dependence on the IMF. The estimated perturbations are compared with observations from the ground and from the low-altitude polar orbiting satellite Oersted. It is found that the long-distance effect of the high-latitude FACs constitute the major source to IMF B y and B z related magnetic east-west disturbances at mid- and low latitudes.

Received 27 March 2007; accepted 19 June 2007; published 16 August 2007.

Keywords: field-aligned currents; IMF By; low latitude perturbation.

Index Terms: 2721 Magnetospheric Physics: Field-aligned currents and current systems (2409); 1541 Geomagnetism and Paleomagnetism: Satellite magnetics: main field, crustal field, external field; 2784 Magnetospheric Physics: Solar wind/magnetosphere interactions; 2134 Interplanetary Physics: Interplanetary magnetic fields; 1650 Global Change: Solar variability (7537).

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Citation: Vennerstrom, S., F. Christiansen, N. Olsen, and T. Moretto (2007), On the cause of IMF By related mid- and low latitude magnetic disturbances, Geophys. Res. Lett., 34, L16101, doi:10.1029/2007GL030175.