Magnetosheath parameters near the subsolar line predicted by an MHD flow model with anisotropic pressure


We extend our “magnetic string” MHD model describing the flow of the shocked solar wind around the magnetosphere to include an anisotropic plasma pressure with p⊥ > p‖. Thermodynamic properties are determined by the law of conservation of energy of a magnetic string associated with a magnetic field line. The MHD equations are closed by a relation between p⊥ and p∥ corresponding to the threshold of the electromagnetic proton cyclotron wave instability. Assuming no flow across the magnetopause, we compare profiles of the steady-state magnetic field and plasma parameters along the subsolar line for upstream sonic and Alfvén Mach numbers = 10 with the isotropic case (p⊥ = p‖). In the anisotropic model, besides the density, both temperatures, plasma pressures and betas decrease toward the magnetopause. The temperature and plasma pressure parallel to the magnetic field decrease more strongly than those perpendicular to the field. Profiles for temperature and pressure in the case of isotropy lie between those of corresponding parallel and perpendicular values, but closer to the latter. The gradient of B near the magnetopause is larger than for isotropic pressure.

Publication Date


Journal Title

Advances in Space Research



Digital Object Identifier (DOI)

Document Type