Authors: Monika Karki (University of Alabama in Huntsville), Laxman Adhikari (University of Alabama in Huntsville), Gary Zank (University of Alabama in Huntsville)

Anisotropy is an important property of solar wind fluctuations describing the changes in the properties of turbulence with respect to direction relative to the magnetic field. We present an observational study of anisotropic turbulence in the slow solar wind, focusing on outward and inward Elsässer energy, fluctuating magnetic energy density, fluctuating kinetic energy, total turbulence energy, cross helicity, residual energy, and the corresponding correlation lengths between the Sun and the Earth. We utilize observations from Parker Solar Probe, Solar Orbiter, Solar and Heliospheric Observatory (SOHO), and STEREO. First, we calculate the transverse turbulence energies and their correlation length. Then, based on the transverse turbulence components, we derive the 2D and slab turbulence energy and their corresponding 2D and slab correlation lengths respectively by using the criteria of (i) 65°< θ_UB < 115°and (ii) 0°< θ_UB < 25° or 155°< θ_UB < 180°, where θ_UB is the angle between the mean solar wind speed and the mean magnetic field. Similarly, we derive the 2D and slab turbulence cascade rate as a function of distance. Our study determines how i) the 2D and slab turbulence energies (and their ratio); ii) the 2D and slab correlation lengths (and their ratio), and the iii) 2D and slab heating rates (and their ratio), vary as a function of distance between the Sun and the Earth.