MM5 (weather model)

The Mesoscale Meteorology Model MM5 5 or short is a computer program for modeling for weather forecasting in the central and regional level, called a Limited Area Model.

The program allows the simulation and prediction of atmospheric circulation and thus numerical weather prediction with resolutions ranging from about 1 to 100 km. It was developed at the Pennsylvania State University (PSU ) and the National Center for Atmospheric Research (NCAR ) as a " Community Model ".


MM5 is a grid-based model with ground- following coordinates. The essential characteristics of MM5 are the Mult Ines Ting capability including a flexible nest, non- hydrostatic dynamics, which allows the simulation of processes below 10 km resolution, full platform-independent parallelization or vectorization (MPI, OpenMP, and HPF ) for different computer architectures, four-dimensional data assimilation and a variety of different options for the treatment of the physical processes. These include the cloud and precipitation formation, exchange processes in the boundary layer and on the ground, as well as the long-and short -wave atmospheric radiation processes. Docked is a soil, snow and vegetation model for calculating the heat and moisture budget in the upper soil layers.

Construction and components

The full model system consists besides the actual MM5 simulation program of a chain of pre-and postprocessor programs. The first module of the Preprocessorkette ( TERRAIN ) defines the model area and is preparing to geographical input data, ie, among others, orography, vegetation and soil type on. Then meteorological input data ( given on pressure surfaces atmospheric flow, humidity, temperature and Geopotentialfelder, and mean sea level pressure ) from global circulation models by another module ( REGRID ) are processed. The meteorological input data set can be supplemented by additional soil and radiosonde observations ( RAWINS or LITTLE_R ). Another module ( INTERP ) performs vertical interpolation of the atmospheric input data of the pressure areas on the terrain following coordinates used by MM5 through and provides initial conditions, and the required for the entire simulation period boundary conditions. This is necessary because MM5 regarded as limited -area model only a limited part of the atmosphere. A detailed description of all MM5 options, as well as all pre-and postprocessor programs can be found on the MM5 homepage and Dudhia ( 2000).

MM5 is no longer being developed as of version 3.7, as developed by NOAA Weather Research and Forecasting model Succession Model ( WRF ) has been released in version 3.1 and available to users worldwide.


  • ( Grell, 1994) Grell, GA, Dudhia, J. and Stauffer, DR, 1995. A description of the fifth generation Penn State / NCAR mesoscale model ( MM5 ). Technical report, National Center for Atmospheric Research, Boulder, Colorado, USA. NCAR/TN-398 STR.
  • ( Dudhia 1993), Dudhia, J., A nonhydrostatic version of the Penn State - NCAR mesoscale model: Validation tests and simulation of an Atlantic cyclone and cold front, Monthly Weather Review, vol. 121, pp. 1493-1513, 1993
  • ( Dudhia 2000), Dudhia, J., PSU / NCAR Mesoscale Modeling System Tutorial Class Notes and User 's Guide: MM5 Modeling System Version 3, NCAR, 2000