Internally and externally induced deformations of the magnetospheric equatorial current as inferred from spacecraft data

N. A. Tsyganenko, V. A. Andreeva, and E. I. Gordeev


Abstract. Based on a data pool of 79 yearly files of space magnetometer data by Polar, Cluster, Geotail, and Themis satellites between 1995 and 2013, we developed a new quantitative model of the global shape of the magnetospheric equatorial current sheet as a function of the Earth's dipole tilt angle, solar wind ram pressure, and interplanetary magnetic field. This work upgrades and generalizes an earlier model of Tsyganenko and Fairfield (2004) by extending the modelling region to all local times, including the dayside sector. In particular, an essential feature of the new model is the 'bowl-shaped' tilt-related deformation of the equatorial surface of minimum magnetic field, similar to that observed at Saturn, whose existence in the Earth's magnetosphere has been demonstrated in our recent work (Tsyganenko and Andreeva, 2014).
Accepted for publication by Annales Geophysicae, November 28, 2014.