MHD turbulence power anisotropy with compressibility at 1 au

We study the turbulence power anisotropy with compressibility using OMNI datasets over a period of 25 years from January 1st, 1995 to January 1st, 2020 at 1 au. Using method M1 (Belcher & Davis 1971), we calculate the transverse and parallel variances of the outward and inward Elsasser energy, fluctuating magnetic energy, and fluctuating kinetic energy. In addition to the transverse and parallel turbulence energies, we calculate the corresponding correlation lengths using method M2 (Adhikari et al. 2022). The transverse turbulence components can be regarded as incompressible components. The parallel turbulence components can be regarded as compressible components. We find that both the methods yield similar transverse and parallel turbulence energies and depend on the solar cycle. We find that traverse energy is always larger than parallel energy. We find that the transverse and parallel Elsasser energy ratio depends on the solar cycle. We find that transverse and parallel correlation length were similar for their respective energy. We find that incompressible turbulence is strongly dominated by transverse turbulence magnetic energy. We find that compressible turbulence is mainly dominated by parallel turbulence magnetic energy; however, in some cases, it can be dominated by parallel turbulence kinetic energy.