The interplanetary magnetic field Bz-component influence on the geomagnetic field variations and on the auroral dynamics

Abstract

The influence of the interplanetary magnetic field (IMF) B z-component on the geomagnetic field variations and on the auroral dynamic are examined. The following results are obtained: 1. (1) The negative (positive) pulse in the B z-component of the IMF caused the current from the nightside to the dayside (from the dayside to the nightside) in the polar cap and the eastward (westward) current at the Equator. 2. (2) In the interval 08–14 L.T. the fluctuations of the B z-component always provoke those of the magnetic field's H-component at the magnetic Equator, the relationship between them being expressed in the form: ΔH = −4 ΔB z. In the interval 14–17 L.T. this relationship could not always be revealed. 3. (3) There is a tendency to an increase (decrease) of the 3 h mean intensity of the equatorial electrojet with an increase (decrease) of the B z-component average values. 4. (4) The variations of the equatorial boundary of aurorae in the interval 08–20 M.L.T. with a duration of 30–60 min are synchoronous with the occurrence and the increase of the DP-2 current system. The dependence of the equatorial auroral boundary position in the noon sector, on the horizontal disturbance vector value in the polar cap is expressed by the relation: Δφ′( km)=(4.0 ±1.0)ΔT(γ) 5. (5) The region in which the direction of the auroral discrete forms meridional motion changes, consists of a system of longitudinal overlapping arcs of the noon and the evening types. The short-lived noon rayed arcs always occur in this region at lower latitudes than the homogeneous evening arcs. During the period of DP-2 increase the short-lived noon arcs and the evening arcs move towards each other.