A description of the fifth-generation Penn State/NCAR Mesoscale Model (MM5)

This technical report describes the fifth generation Penn State/NCAR Mesoscale Model, or MM5. It is intended to provide scientific and technical documentation of the model for users. Source code documentation is available as a separate Technical Note (NCAR/TN-392) by Haagenson et al. (1994). The document structure is as follows: In section 2 we describe the governing equations, algorithms, and boundary conditions. This will include the finite difference algorithms and time splitting techniques of both the hydrostatic and the nonhydrostatic equations of motion (hydrostatic and nonhydrostatic solver). All subsequent sections will describe features common to both solvers. Section 3 discusses the mesh-refinement scheme, section 4 the four-dimensional data-assimilation technique, and section 5 focuses on the various physics options.