Jump conditions for pressure anisotropy and comparison with the Earth's bow shock

Taking into account the pressure anisotropy in the solar wind, we study the magnetic field and plasma parameters downstream of a fast shock, as functi ons of upstream parameters and downstream pressure anisotropy. In our theor etical approach, we model two cases: a) the perpendicular shock and b) the oblique shock. We use two threshold conditions of plasma instabilities as a dditional equations to bound the range of pressure anisotropy. The criterio n of the mirror instability is used for pressure anisotropy P (perpendicula r to)/P (parallel to) > 1. Analogously, the criterion of the fire-hose inst ability is taken into account for pressure anisotropy P-perpendicular to/P- parallel to < 1. We found that the variations of the parallel pressure, the parallel temperature, and the tangential component of the velocity are mos t sensitive to the pressure anisotropy downstream of the shock. Finally, we compare our theory with plasma and magnetic field parameters measured by t he WIND spacecraft.