Quantitative model of the Martian magnetopause shape and its variation with the solar wind ram pressure based on Phobos 2 observations

Abstract

A model of the Martian magnetopause is developed for the period of maximum solar activity which simultaneously describes (1) the observed relation between the solar wind ram pressure ρ V 2 and the magnetopause position in the magnetotail, (2) the observed relation between ρ V 2 and the flaring angle, and (3) a few magnetopause crossing observations above the day side of the planet. The shape of the magnetopause is determined from the equation of pressure balance across this boundary when both the magnetic pressure (with a planetary magnetic moment of (0.8–1.0)×l0 22 G cm 3 ) and the ionospheric pressure are taken into account in the planetary magnetosphere. The specific feature of the model is the “stagnation” of the subsolar magnetopause when the ram pressure increases to higher values (≥ 6×10 −9 dyn cm −2 ).