In HAFS, horizontal and vertical turbulent mixing is parameterized separately in FV3 dynamic core and a one-dimensional module in CCPP, respectively. This method becomes problematic as model resolution increases to the gray zone where three-dimensional (3D) turbulent processes become important.
To remediate the problem, a 3D scale-aware (SA) turbulent kinetic energy (TKE) scheme applicable to the gray zone has been developed for the UFS models and implemented in HAFS.