Phase coherence in the turbulent solar wind: a comparative study

M. S. NAKWACKI; M. E. RUIZ; DASSO, S.

Ciudad Autonoma de Buenos Aires

Congreso; Fluidos 2012; 2012

The solar wind (SW) is a suitable natural scenario to study the intermittent nature of magnetohydrodynamic(MHD) turbulence for systems with low dissipation rate. The degree of phasecorrelation and departures from Gaussianity can be used to characterize nonlinear wave-wave interactionsin such media. The SW plasma is a system in conditions close to thermal equilibriumand it frequently presents thermal anisotropies respect to the mean magnetic field. In this workwe compare numerical simulations and in situ observations of the SW, with emphasis on studyingphase correlation and departures from Gaussianity for the fluctuations in the system. Thehigh-resolution numerical simulations are done in a theoretical frame of a kinetic MHD formalismwith a Chew-Golberger-Low double-isothermal closure (CGL-MHD) for a compressible fluid (i.e.,CGL-MHD equations), emulating SW conditions. In situ observations from the spacecraft ACE,which is located near one astronomical unit from the Sun, in the SW near Earth, are also analyzedand compared with the simulations. In particular, we compute the phase coherence index for both,the temporal data series of the observed magnetic field and the simulated turbulent field, in orderto quantify the effects of such nonlinear interactions.