Comparison of simulated and observed large-scale, field-aligned current structures

• Main Author: P. Nenovski
• Format: Article
• Language: English
• Published: Copernicus Publications 2008-02-01
• Series: Annales Geophysicae
• Online Access: https://www.ann-geophys.net/26/281/2008/angeo-26-281-2008.pdf

Recently, a model of large-scale, field-aligned current (FAC) structures, based on zero-frequency MHD surface wave (SW) modes that can emerge from the solar wind-Earth's magnetosphere interaction, has been proposed. The FAC polarity and intensity distribution are quantified as a function of the solar wind parameters and the interplanetary magnetic field (IMF) magnitude that enter as input parameters. Besides, there are input parameters intrinsic to the Earth's magnetosphere &ndash; the size of the polar cap and the boundary regions and their plasma density variations. Influence of the IMF <I>B_y</I> component on the FAC structure is examined here. Depending on the IMF <I>B_y</I> magnitude, the predicted six-cell FAC structure tends to evolve in a spiral-like fashion. This large-scale FAC model is compared with experimental evidences and empirical FAC models based on DE-2 satellite data and high-precision Oersted and Magsat satellite magnetometer data. Among the various achievements of these long-term satellite measurements, an observation/discovery of a ground-based state of FACs which includes a pair of large-scale FACs in the polar cap under both positive and negative IMF <I>B_z</I> has been pointed out. The FAC pattern is qualitatively and quantitatively consistent with experimental data for both polar cap FAC and Region 1 and Region 2 FAC systems.