Alfvénic turbulence in high-latitude solar wind: Radial versus latitudinal variations

Abstract

Plasma and magnetic field measurements by Ulysses during its first out-of-ecliptic orbit have allowed extensive investigations on the behavior of Alfvénic turbulence in high-latitude solar wind from 1 to 5 AU. Most analyses have shown that the turbulence evolution in high-latitude wind is radial, rather than latitudinal, in nature. However, a recent study, based on magnetic field fluctuations, has suggested that latitudinal effects might play a nonnegligible role. Here we further examine this possibility by using Elsässer's variables, quantities that directly are related to the Alfvénic content of solar wind fluctuations. Our conclusion, supported by a comparison between polar and ecliptic observations, is that latitude does not appear to have an appreciable influence on the turbulence evolution in high-latitude solar wind.