title: Compressibility in solar wind plasma turbulence.
abstract: Incompressible magnetohydrodynamics is often assumed to describe solar wind turbulence. We use extended self-similarity to reveal scaling in the structure functions of density fluctuations in the solar wind. The obtained scaling is then compared with that found in the inertial range of quantities identified as passive scalars in other turbulent systems. We find that these are not coincident. This implies that either solar wind turbulence is compressible or that straightforward comparison of structure functions does not adequately capture its inertial range properties.
authors.affiliation: Physics Department, University of Warwick, Coventry, CV4 7AL, United Kingdom. hnat@astro.warwick.ac.uk
authors.forename: Bogdan
authors.initials: B
authors.lastname: Hnat
authors.forename: Sandra C
authors.initials: SC
authors.lastname: Chapman
authors.forename: George
authors.initials: G
authors.lastname: Rowlands