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Diagnosis of Magnetic Structures and Intermittency in Space Plasma Turbulence using the Method of Surrogate DataSeveral observations in space plasmas have reported the presence of coherent structures at different plasma scales. Structure formation is believed to be a direct consequence of nonlinear interactions between the plasma modes, which depend strongly on phase synchronization of those modes. Despite this important role of the phases in turbulence, very limited work has been however devoted to study the phases as a potential tracers of nonlinearities in comparison with the wealth of literature on power spectra of turbulence where phases are totally missed. We present a method based on surrogate data to systematically detect coherent structures in turbulent signals. The new method has been applied successfully to magnetosheath turbulence (Sahraoui, Phys. Rev. E, 2008, in press), where the relationship between the identified phase coherence and intermittency (classically identified as non Gaussian tails of the PDFs) as well as the energy cascade has been studied. Here we review the main results obtained in that study and show further applications to small scale solar wind turbulence. Implications of the results on theoretical modelling of space turbulence (applicability of weak/wave turbulence, its validity limits and its connection to intermittency) will be discussed.
Document ID
20080039167
Document Type
Conference Paper
Authors
Sahraoui, Fouad (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Goldstein, Melvyn (Centre National de la Recherche Scientifique Velizy, France)
Date Acquired
August 24, 2013
Publication Date
September 22, 2008
Subject Category
Astrophysics
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.