New developments in RAP/HRRR Model Physical Parameterizations: MYNN-Eddy Diffusivity/Mass-Flux PBL Scheme with a Mixing Length Revision
Parallel efforts to improving the eddy diffusion component of the EDMF include a revision of the mixing length formulation in the MYNN PBL scheme. The primary motivation is to improve simulations of the stable boundary layer by testing a “z-less” mixing length approach. Both idealized and case study testing show improved low-level jets and cold pool formation/maintenance. The new EDMF scheme improves aspects of the RAP/HRRR forecasts, such as low-level winds and the stratification at the top of the convective boundary layer, which have particular importance for renewable energy and convective forecast applications.