The shape and location of the high-latitude magnetopause

Abstract

Recent empirical magnetopause models are bi-variate with respect to both solar wind dynamic pressure and B Z component of the interplanetary magnetic field (IMF). Models use various functional forms to represent the shape and location of the magnetopause. Moreover, the models have different ranges of validity because, among other things, the data sets used for their development were usually different. A majority of these models were created for magnetopause crossings regardless of latitude. For the shape of the near-Earth high-latitude magnetopause, a new empirical model was published by Boardsen et al. [Boardsen, S.A., Eastman, T.E., Sotirclis, T, Green, J. L. An empirical model of the high-latitude magnetopause. J. Geophys. Res. 105, 23,193, 2000]. This model is parameterized by solar wind dynamic pressure, IMF B Z and dipole tilt angle. However, this model covers only a high-latitude part of the magnetopause in a limited range of the X GSE coordinate (∼±8 R E). We have used a new set of high-latitude magnetopause crossings and compared their coordinates with predictions of several magnetopause models with motivation to analyze differences between measurements and models. Our study reveals that the effect of the near-cusp magnetopause indentation can be reflected by an addition of a simple geometrical formula to the generally accepted model. This approach provides an universal model which describes the whole magnetopause surface with sufficient accuracy regardless of latitude.