Meeting abstract

Solar Wind 9, Nantucket, 5-9 October 1998

Abstract:
The behaviour of MHD fluctuations in a steady expanding solar wind is not well understood. The Ulysses spacecraft has recently sampled the polar heliosphere near solar minimum over a wide range of latitudes and distances in just such a steady flow. The magnetic field and plasma experiments on the spacecraft have provided a unique data set for the study of magnetohydrodynamic waves and turbulence unaffected by large-scale stream structure.

We discuss previous results and present a new analysis of Ulysses polar data, including measurements of power levels, anisotropy and spectral indices of both magnetic field and Elsasser variable fluctuations, as functions of wavenumber, latitude and distance in the polar heliosphere. In addition to confirming earlier work, we present several new results concerning latitude dependence of the fluctuations. In addition, we compare Ulysses polar data and Helios measurements of fluctuations in high speed streams between 0.3 and 1 AU.