Anomalous compressible mode generation by global frame projections of pure Alfven mode

ABSTRACT Alfven wave is the single most important physical phenomenon of magneto-hydrodynamic (MHD) turbulence and has far-reaching impact to almost all studies related astrophysical magnetic field. Yet restoration fluctuations from a given field, aka local problem, never properly addressed in literature albeit its importance. Previous works model fluctuation as perturbation along straight-line, constant However, Lazarian & Pogosyan (2012) suggested that decomposition straight line, aka. global frame decomposition, factor discrepancy true fluctuation. Here, we provide geometric interpretation on how through use vector formulation. We prove both analytically numerically an orthogonal transformation by Alfvenic Mach number. In other words, when observe reference, some will be mistaken compressible waves. The importance choices analytical MHD turbulence. Combining formalism new techniques can have accurate measurement fundamental properties like inclination angle mean field relative line sight.