TRANSMISSION OF ALFVEN WAVES THROUGH EARTHS BOW SHOCK

The transmission of Alfvén waves through the Earth's bow shock is calculated on the basis of the theory of hydromagnetic shocks. For conditions typical of the solar wind it is shown that the amplitude of the magnetic field of the transmitted Alfvén wave is about three times larger than that of the incident, and, in addition, another Alfvén wave is generated with amplitude roughly equal to the incident wave amplitude. Since longitudinal waves are greatly amplified on passage through strong shocks and, as shown in this paper, transverse Alfvén waves undergo only moderate amplification, the energy flux of long wavelength waves in the magnetosheath ought to be predominantly in acoustic-type waves than in transverse waves. © 1969.