Integrating a Three-Dimensional TKE-Based Subgrid Diffusion Scheme Into GFDL FV3
Abstract
We present the implementation of an inline three-dimensional (3D) turbulent kinetic energy (TKE)-based subgrid diffusion scheme in the Geophysical Fluid Dynamics Laboratory (GFDL) Finite-Volume Cubed-Sphere (FV3) dynamical core. This scheme addresses the need for a unified and physically grounded treatment of turbulence as FV3 is increasingly used across the gray zone and large-eddy simulation scales. Building on the 3D TKE framework introduced in Zhu et al. (2025), we embed the full TKE budget calculations, including the 3D shear production, and TKE-informed horizontal and vertical diffusion directly into the FV3 core. Key features include computation of 3D TKE shear production based on FV3 D-grid winds, updating of TKE and diffusion coefficients within the FV3 time-stepping loop, and extension of TKE-based horizontal diffusion to all dynamical fields.
