A relationship is derived between power anisotropy and wavevector anisotropy
in turbulent fluctuations. This can be used to interpret plasma turbulence
measurements, for example in the solar wind. If fluctuations are anisotropic in
shape then the ion gyroscale break point in spectra in the directions parallel
and perpendicular to the magnetic field would not occur at the same frequency,
and similarly for the electron gyroscale break point. This is an important
consideration when interpreting solar wind observations in terms of anisotropic
turbulence theories. Model magnetic field power spectra are presented assuming
a cascade of critically balanced Alfven waves in the inertial range and kinetic
Alfven waves in the dissipation range. The variation of power anisotropy with
scale is compared to existing solar wind measurements and the similarities and
differences are discussed.Comment: 5 pages, 3 figures, published versio