title: Nonaxisymmetric anisotropy of solar wind turbulence as a direct test for models of magnetohydrodynamic turbulence.
abstract: Single point spacecraft observations of the turbulent solar wind flow exhibit a characteristic nonaxisymmetric anisotropy that depends sensitively on the perpendicular power spectral exponent. We use this nonaxisymmetric anisotropy as a function of wave vector direction to test models of MHD turbulence. Using Ulysses magnetic field observations in the fast, quiet polar solar wind we find that the Goldreich-Sridhar model of MHD turbulence is not consistent with the observed anisotropy, whereas the observations are well reproduced by the "slab+2D" model. The Goldreich-Sridhar model alone cannot account for the observations unless an additional component is also present.
authors.affiliation: Centre for Fusion, Space and Astrophysics, University of Warwick, Coventry, United Kingdom. a.j.turner@warwick.ac.uk
authors.forename: A J
authors.initials: AJ
authors.lastname: Turner
authors.forename: G
authors.initials: G
authors.lastname: Gogoberidze
authors.forename: S C
authors.initials: SC
authors.lastname: Chapman