Effect of the meridional velocity gradient on the anisotropy of turbulence in the solar wind

Abstract

In this paper, the heliolatitude dependence of the anisotropy of hourly interplanetary magnetic field fluctuations under conditions characteristic of low solar activity is studied. Measurements carried out by the Ulysses spacecraft in 1992–1994 and 1995–1997 are analyzed. It is found that the minimum fluctuation variance axis has a significant tilt toward the helioequator at low heliolatitudes. The Ulysses data processing has shown that this feature can be caused by the inclination of magnetohydrodynamic waves under the influence of the solar wind meridional velocity gradient.