Anisotropic Third-Moment Estimates of the Energy Cascade in SolarWind Turbulence Using Multispacecraft Data

OSMAN, K.T.; WAN M.; MATTHAEUS W.H.; WEYGAND J.M.; DASSO S.

PHYSICAL REVIEW LETTERS

AMER PHYSICAL SOC

Lugar: New York; Año: 2011 vol. 107 p. 165001 - 165006

0031-9007

The first direct determination of the inertial range energy cascade rate, using an anisotropic form ofYaglom?s law for magnetohydrodynamic turbulence, is obtained in the solar wind with multispacecraftmeasurements. The two-point mixed third-order structure functions of Elsa¨sser fluctuations are integratedover a sphere in magnetic field-aligned coordinates, and the result is consistent with a linear scaling.Therefore, volume integrated heating and cascade rates are obtained that, unlike previous studies, makeonly limited assumptions about the underlying spectral geometry of solar wind turbulence. These resultsconfirm the turbulent nature of magnetic and velocity field fluctuations in the low frequency limit, andcould supply the energy necessary to account for the nonadiabatic heating of the solar wind.