Pc5 pulsations on the ground, in the magnetosphere, and in the electron precipitation: event of 19 January 2005

Abstract

In the first part of our paper, we consider the pattern of geomagnetic pulsations in the Pc5 range in the North European area, based on an event of 19 January 2005. Intense pulsations, observed in Lovozero at Kola Peninsula, were accompanied by auroras north of the station, recorded by an all-sky TV camera. In the second part, we consider the global pattern of amplitudes and phases of geomagnetic pulsations for this event, which includes data from nearly conjugate stations and the magnetic data of GOES 10 and 12, confirming the quasi-stationary model for magnetic field distribution on the ground. In the event, the auroral luminosity oscillated with the same 5 min period as the magnetic field. Magnetic data from Scandinavia and data from North Europe riometers show analogous pulsations. The maximal intensity of geomagnetic pulsations in this region occurred near the pulsating aurora, but there was a reversal of pulsation polarity in the X-component. In the area of phase change the value of the Z-component is maximal. We suggest that geomagnetic pulsating variations, observed on the surface, are determined by Biot-Savart's law for a three-dimensional current system, the extra-ionospheric part of which is spatially coincident with auroral electron flux. The electric field in the ionosphere is found from the current continuity condition and the value of Pedersen conductivity. The directions to the pulsating current, calculated by using the magnetic data from Lovozero, are close to the directions of the auroral area. We also claim that this approach is applicable to all short periodic oscillations observed on the surface. Satellite data indicates the same periods, but with oscillations that appear to be poloidal on GOES10 and toroidal on GOES12, suggesting the traveling character of the wave. Copyright 2008 by the American Geophysical Union.