INFLUENCES OF THE VARIATIONS OF SOLAR WIND STATE ON THE MAGNETIC FIELD FLUCTUATION CHARACTERISTICS IN EARTH'S MAGNETOSHEATH

Influences of the variations of the background solar wind parameters, Alfvenic Mach number M₁, plasma β₁ value and magnetic field angle 61, on the state and spatial distribution of the magnetic field fluctuations in the Earth's magnetosheath are discussed using the exact solution of MHD shock wave jump conditions. The results show that: (1) M₁ mainly controls the level of the amplitude, the relative fluctuation and the anisotropic degree of magnetic field fluctuations. θ₁ controls the spatial distribution of magnetic field fluctuation characteristics. β₁ value does not produce obvious variations of the state of magnetic field fluctuations; (2) While the state of background solar wind changes, the variations of the state of magnetic field fluctuations behind the bow shock will be asymmetric, this responses to the change of background solar wind parameters, M₁, β₁, almost only occur in the dawn side of the magnetosheath. The dawn side is very active in the fluctuations or turbulences of magnetic field, but the dusk side is stable; and (3) This responses to M₁,β₁ at different places are similar, but to θ₁ parameter, the responses show very different form.