Amplification of hydromagnetic waves through the earth's bow shock

Abstract This paper sets out to determine if the turbulence observed in the magnetosheath can be generated by amplification, through the Earth's bowshock, of the hydromagnetic fluctuation carried by the solar wind. This problem is closely related to the study of the transmission and generation of hydromagnetic waves through an oblique fast shock wave. An incident wave (Alfven, magnetosonic or entropy wave) striking the front of the shock, is refracted and gives rise to five other hydromagnetic waves. In this paper, a system of equationsis given to determine the transmission and generation coefficients of these diverging waves. Given a model of the Earth's bow shock, the ratio of refracted to incident energy fluxes is computed. It appears that there is always amplification, at least for one refracted wave, but its value varies greatly with the direction of the incident wave. Therefore, further information about the angular distribution of the hydromagnetic perturbations carried by the solar wind are required to give an order of magnitude of the energy of the turbulence created.