Multiple same-level and telescoping nesting in GFDL's dynamical core

Two-way multiple same-level and telescoping grid nesting capabilities are implemented in the Geophysical Fluid Dynamics Laboratory (GFDL)'s Finite-Volume Cubed-Sphere Dynamical Core (FV3). Simulations are performed within GFDL's System for High-resolution modeling for Earth-to-Local Domains (SHiELD) using global and regional multiple nest configurations. Results show that multiple same-level and multi-level telescoping nests were able to capture various weather events in greater details by resolving smaller-scale flow structures. Two-way updates do not introduce numerical errors in their corresponding parent grids where the nests are located. The cases of Hurricane Laura's landfall and an atmospheric river in California were found to be more intense with increased levels of telescoping nesting. All nested grids run concurrently, and adding additional nests with computer cores to a setup does not degrade the computational performance nor increase the simulation run time if the cores are optimally distributed among the grids.