The following subsections provide a brief overview of the science and options that are available in MM5. A description of the standard MM5 options is found in Grell et al. [1995]. The source code for MM5 is documented in Haagenson et al. [1994].
MM5 is the fifth-generation Penn State/NCAR mesoscale model. It has grown from the model used by Anthes in the early 1970s that was documented in Anthes and Warner [1978]. The improvements in MM5 over the previous version (MM4) include the option for non-hydrostatic physics, as well as more sophisticated explicit moisture, boundary layer processes, radiation, convective parameterization, among other improvements. Dudhia [1993] documents the major changes from MM4 to MM5. Starting with MM5 Version 2 (MM5v2), the software has been restructured to run on various hardware platforms in addition to the Cray, with emphasis placed on workstation-based MM5 simulations. The latest is MM5 Version 3 (MM5v3) and is the recommended version for CMAQ simulations.