MM5 Model Description
Real-time forecasts are currently produced using the PC Linux versions developed by Applied Modeling Inc. (AMI) of the advanced, three-dimensional mesoscale model MM5 (Version 3). The MM5 mesoscale model is a limited-area, nonhydrostatic, terrain-following sigma-coordinate model designed to simulate or predict mesoscale and regional-scale atmospheric circulation. It has been developed at Penn State University and National Center of Atmospheric Research (NCAR) since the 1970s as a community mesoscale model. It is continuously being improved by contributions from several universities and government laboratories as well as private consulting firms around the world.
The MM5 forecast covers most of Southeast Asia, from south China in the north to north Borneo in the south, and Thailand in the west to the Phillipines in the east. As shown the plot below, the outer domain (domain D01) consists of 41 x 53 grid points, spaced 72 km apart with 23 vertical levels. The inner domain (domain 02) consists of 67 x 82 grid points, spaced 24 km apart also with 23 levels. Key parameterizations of physical processes include:
National Centers for Environmental Prediction (NCEP) MRF planetary boundary
Explicit moisture scheme (including simple ice physics but no mixed phase processes)
Grell (1993) cumulus parameterization
Dudhia (1989) radiation scheme
5-layer soil model
Initial conditions are generated by interpolating the NCEP AVN analyses to the MM5 grids. Lateral boundary conditions are derived from the AVN forecasts.
The initialization and 48h forecasts for both grids are completed in about 4 hours on an Intel Pentium 4 1.4 Ghz Linux PC . Two MM5 forecasts, valid for 48 hours, are available daily for 00 UTC (0700 Vietnam time) and 12 UTC (1900 Vietnam time). The 00 UTC forecast is usually available around 7:30 AM Vietnam time while the 12 UTC run should be completed by 7:30 PM Vietnam time. In the event of storms, two additional forecasts are available for 1 AM and 1 PM Vietnam time.
Last modified: May 21, 2001