Geomagnetopause Position and Shape Dependence on Solar Wind Plasma and IMF Parameters: Analytic Model Comparison with Observations and 3-D MHD Runs

Abstract

It is generally accepted to use the solar wind ram pressure ρV2 and the IMF Bz component for empirical description of the geo-magnetopause position and shape. A specific feature of the present paper is not to use the solar wind ρV2 but the thermal Pth and magnetic field Pmag pressures adjacent to the magnetopause for proper modelling. These pressures are deduced from the results of 3-D MHD runs and analytic solutions for post bow shock MHD flow in Lagrangian variables. The magnetopause shape variation due to Bz component changes the so called ‘doubling factor’ fd, which can be analytically deduced from a Tsyganenko magnetospheric field ellipsoidal model. Including all the above effects in our analytical model leads to a good description of ‘rapid’ magnetopause approach to the Earth for southward IMF and to its ‘stagnant’ behaviour with the increase of northward IMF component.

Physics‐Based Analytical Model of the Planetary Bow Shock Position and Shape

“…To address the shortcomings of both computational and empirical models M. I. Verigin with co‐authors developed a semiempirical approach for modeling different plasma boundaries and regions in space (G. Kotova et al., 2005, 2020; G. A. Kotova et al., 2015, 2020; M. Verigin, 2004; M. Verigin et al., 1997, 2001, 2004; Verigin, Slavin, Szabo, Gombosi, et al., 2003; Verigin, Slavin, Szabo, Kotova, et al., 2003; M. I. Verigin et al., 1997, 1999, 2001, 2004, 2009, 2018). This approach is based on maximum use of exact analytical solutions that describe some characteristic properties of the phenomenon, for example, the asymptotic MHD Mach cone.…”