Methods of plasma turbulence analysis: Application to shock studies

The availability of multisatellite observations (e.g. ISEE, AMPTE, and Cluster) has triggered the development of new methods of analysis to shed light on the complex dynamics inherent in the solar wind and magnetosphere. This paper looks at the results of two such methods. Firstly, the phase differencing method is used to determine the properties of waves observed upstream of a quasiperpendicular bow shock. The resulting dispersion relation is then interpreted as evidence that the waves are generated as a result of the dynamics of the shock front. The second, NARMAX, is used to investigate the linear and nonlinear processes if the plasma observed at a antiparallel shock. The results show that for a small amplitude whistler wavetrain, third order nonlinear interactions are only important at the interface between the shocklet and the wavetrain. For higher amplitude wavetrains, the phase of the linear term describing the plasma is shifted.