Indexed on: 01 Feb '15Published on: 01 Feb '15Published in: Geomagnetism and Aeronomy
Dependence of the spectral slope of long-period high-latitude Pc5/Pi3(1–5 mHz) geomagnetic variations on parameters of the interplanetary geomagnetic field and plasma in front of the bow shock and in the magnetosheath is analyzed for different intervals of the local magnetic time. It is shown that, contrary to the power spectral density, for which the coherent variations on 103 km scales are controlled by the plasma parameters in front of the bow shock, coherent variations of the spectral slope are controlled by processes in the magnetosheath. The relation between the spectral slope at geomagnetic latitudes Φ > 73° and the parameters of the magnetic field in the magnetosheath was established. Thus, the spectral slope of high latitude disturbances in the 1–5 mHz frequency range reflects processes in the magnetosheath, far from the subsolar point, and cannot be predicted with only an analysis of parameters in the interplanetary media in front of the bow shock.