The PSU/NCAR mesoscale model is a limited-area, nonhydrostatic or hydrostatic (Version 2 only), terrain-following sigma-coordinate model designed to simulate or predict mesoscale and regional-scale atmospheric circulation. It has been developed at Penn State and NCAR as a community mesoscale model and is continuously being improved by contributions from users at several universities and government laboratories.
The Fifth-Generation NCAR / Penn State Mesoscale Model (MM5) is the latest in a series that developed from a mesoscale model used by Anthes at Penn State in the early 70's that was later documented by Anthes and Warner (1978). Since that time, it has undergone many changes designed to broaden its usage. These include (i) a multiple-nest capability, (ii) nonhydrostatic dynamics, which allows the model to be used at a few-kilometer scale, (iii) multitasking capability on shared- and distributed-memory machines, (iv) a four-dimensional data-assimilation capability, and (v) more physics options.
The model (known as MM5) is supported by several auxiliary programs, which are referred to collectively as the MM5 modeling system.
A schematic diagram (a pdf file, to be opened by Adobe Acrobat Reader) is provided to facilitate discussion of the complete modeling system. It is intended to show the order of the programs and the flow of the data, and to briefly describe their primary functions. Documentation for various programs in the modeling system is available online.
Terrestrial and isobaric meteorological data are horizontally interpolated (programs TERRAIN and REGRID) from a latitude-longitude mesh to a variable high-resolution domain on either a Mercator, Lambert conformal, or polar stereographic projection. Since the interpolation does not provide mesoscale detail, the interpolated data may be enhanced (program RAWINS or little_r) with observations from the standard network of surface and rawinsonde stations using either a successive-scan Cressman technique or multiquadric scheme. Program INTERPF performs the vertical interpolation from pressure levels to the sigma coordinate system of MM5. Sigma surfaces near the ground closely follow the terrain, and the higher-level sigma surfaces tend to approximate isobaric surfaces. Since the vertical and horizontal resolution and domain size are variable, the modeling package programs employ parameterized dimensions requiring a variable amount of core memory. Some peripheral storage devices are also used.
Since MM5 is a regional model, it requires an initial condition as well as lateral boundary condition to run. To produce lateral boundary condition for a model run, one needs gridded data to cover the entire time period that the model is integrated.
The current release for the MM5 modeling system is Version 3. MM5 Version 2, or V2 is also available.
Upperair and surface reports, including wind, temperature, relative humidity, sea-level pressure, and sea surface temperature.
Use other model's output either as first guess for objective analysis, or as lateral boundary conditions, e.g. NCEP and ECMWF global analysis, NCEP/NCAR and ECMWF reanalysis, NCEP ETA model.
Cray, SGI, IBM, DEC, Sun, HP, and PCs running Linux.
Cray (EL, J90, YMP), HP-SPP2000, SGI, SUN and DEC Alpha high performance workstations
IBM RISC 6000 cluster, IBM SP2, Cray T3E, SGI Origin 2000, HP-SPP2000, and Fujitsu VPP
Perform objective analysis: blend first-guess fields with radiosonde and surface observations
Interpolate pressure-level data from either RAWINS or REGRID/DATAGRID to model's sigma coordinate
Perform time integration
Generate plots from the output of modeling system programs (based on NCAR Graphics)
There are several new developments that are either available for testing or underway.
In the past, the 30 sec terrain is only available over continental US. With the newly available global 30 sec terrain dataset, the updated terrain program can produce high resolution terrain field for MM5. The new terrain program can also derive better resolution landuse data from (nearly) global 30 sec vegetation data. This program was released April 7, 1999. This program can be run on Cray as well as workstations. The new terrain also has improved coastline.
This program performs the same function as Datagrid, and has replaced Datagrid in the Version 3 release in the summer of 1999. This program has the advantage of making it easier to access various datasets, and portable to many computer platforms. Users who don't have access to NCAR's computer facility (hence its data), and wish to run programs on workstations are encouraged to use this program.
This program may be used in place of Rawins. Like program REGRID, little_r makes accessing data from sources other than those from NCAR's archive easier. However, not all functions in Rawins are available. In the upcoming Version 3 release, both little_r and Rawins will be supported.
This program has been modified to run on both Cray and workstation platforms since April 1999. It can be obtained from NCAR's anonymous ftp. However this version of Rawins still only uses data from NCAR archive, but converted to workstation format.
This is a completely new model, and is curretly being jointly development by NCAR, NOAA/FSL, NCEP, and CAPS.
The MM5 Version 2/3 models have been run on various machines, including PC running Linux.
All pre-processing programs can now be run on Crays, major workstation vendor machines, and PC running Linux (Version 3 only). Rawins still only accesses data from NCAR archive (with Cray-blocking removed). New programs, REGRID and little_r, are designed to make dealing with data other than those archived at NCAR a lot easier. Both programs are very portable too.
Perhaps the most difficult problem for using the MM5 package on a different site is data acquisition and input. Anyone who is interested in using MM5 should consider if he/she is able to acquire meteorological data, gridded as well as station observations.
The primary reasons we choose this compiler are 1) it supports Cray pointers which are used in MM5 model, and a few other programs; and 2) it has Fortran 90 compiler.
The part of NCAR Graphics required by MM5 modeling system programs has become free to download. For information, please see NCAR Graphics page for details.
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