A systematic approach to decomposing numerical turbulence fields into substructures

We propose a systematic approach for decomposing numerical turbulence fields with both low and high degrees of freedom, extending beyond the conventional division into zonal flow and turbulence. Specifically, we utilize Fourier expansion to decompose turbulence into several substructures where the phase of the kinetic energy density aligns positively or negatively with the zonal flow's poloidal velocity, enabling the separation of turbulence expected to be absorbed into the zonal flow. The proposed methods were successfully applied to simulation datasets we generated, demonstrating their effectiveness in isolating turbulence substructures.