Ramp nonstationarity and the generation of whistler waves upstream of a strong quasiperpendicular shock

Abstract

A number of models have been proposed to explain the observation of low frequency (LF) whistler waves in the upstream region adjacent to the ramp of the quasiperpendicular part of the Earth's bow shock. One such model relates these waves to the nonlinear dynamics of the ramp itself. Two aspects of this model, the plasma frame spectrum of the turbulence and the occurrence of nonlinear waves propagating away from the shock in the upstream region have already been shown to be in agreement with observations. A third aspect, the interaction and energy transfer between these nonlinear waves and the whistler turbulence, is studied by applying high order spectral analysis to Interball magnetic field data. Evidence for the nonlinear coupling between these two types of waves and the possible transfer of energy are presented. Copyright 1999 by the American Geophysical Union.