MM5 (weather model)

Source: Wikipedia, the free encyclopedia.

The MM5 (short for Fifth-Generation Penn State/NCAR Mesoscale Model) is a regional

Penn State University and the National Center for Atmospheric Research. The MM5 is a limited-area, terrain-following sigma coordinate model that is used to replicate or forecast mesoscale and regional scale atmospheric circulation.[1] It has been updated many times since the 1970s to fix bugs, adapt to new technologies, and work on different types of computers and software. It is used in many different ways: for research and for weather prediction. In research, it is used to compare it to other models, to see what works and what does not work. It is also used for air quality models.[2]

Active development on the model ended with version 3.7.2 in 2005, and it has been largely superseded by the Weather Research and Forecasting (WRF) model.[3]

Features

MM5 is globally relocatable, which helps support different latitudes, terrain types, elevations, soil types, etc. . The model can be either

hydrostatic or non-hydrostatic, depending on the desired outcome. The fact that the model is regional implies that it requires initial conditions and lateral boundary conditions. This means that each boundary (there are four) has initialized wind speeds, temperatures, pressure and moisture fields.[4] Thus, gridded data is needed for this program. This model takes and then analyzes its data based on pressure surfaces. However, these surfaces must first be interpolated by a specific vertical coordinate before it can be analyzed.[4] This vertical coordinate, sigma
, is computed and then used throughout the program. Σ is defined as: Σ = (p-pt)/p*, p* = ps-pt, Where p is pressure, ps is surface pressure, and pt is the pressure at the top of the model.[5] When Σ is close to the ground, the program follows the actual terrain, but when Σ is higher up, the program looks at isobaric surfaces. Σ ranges from 0 to 1.[4][6] It has adaptable and multiple nesting capabilities, which allows multiple programs to run at once, while utilizing 2-way nesting. MM5 features inputs from actual data, which is helpful because routine observations can be used. Then, data can be compared and used in context with other models.[6] MM5 also features terrain-following vertical coordinates and four-dimensional data assimilation (FDDA) .[6] FDDA is used when there is a lot of data that was taken over a longer period of time. Then this data that needed to be taken over a longer period of time gets placed into FDDA. It is also utilized for dynamical initialization and four-dimensional data sets.[4] Most importantly, MM5 is well documented and has many places for user support.

Functions

There are many pieces of the MM5 modeling system, each with different functions. These pieces include: TERRAIN, REGRID, LITTLE_R, NESTDOWN, INTERPF, INTERPB, and GRAPH/RIP. In the basic sense, the model begins by taking the information and then makes a model of the land. This is done by using the piece TERRAIN.

NCAR Graphics to help envisage the output from the MM5.[9]

Flow chart of the functions of the MM5

Memory and code basics

MM5 is written in

timesteps, and then delivers the information back to its parent domain.[4]
There are three different ways to do two-way nesting: Nest interpolation, nest analysis input, and nest terrain input.
interpolated.[4]
When multi-tasking occurs, the variables must be marked as either shared or private. Shared implies that the processors all have access to the same part of memory, while private implies that each processor must have its own private copy of an array with its personal memory location.[11] The multi-tasking occurs specifically in the subroutines Solve1, Solve3, and Sound.

Requirements

MM5 can be run in many different ways, depending on the computer. The model can be run on a single processor computer,

disk space.[6]

Source code

The MM5 code itself has over 220

“Cray” pointers. A list of the subroutines of all of the functions within the MM5, with a short description and the routines that are called within it can be found here.[13]

Use

The MM5 had been adapted for use in many different types of atmospheric simulations:

Developments and improvements

TERRAIN's latest update uses USGS global 30 sec terrain elevation data, which looks at the entire world, where before was only used in the continental United States.[21] This new update also allows for a better quality terrain image that can be used in MM5. REGRID's improvement makes it simpler for its users to input the data and it also is more portable.[21] LIITLE_R was developed in 2001 to replace RAWINS. LITTLE_R's improvement again makes it easier for users to input data.[21]

See also

References

  1. ^ "MM5 Community Model Homepage". .mmm.ucar.edu. Retrieved 2022-04-20.
  2. ^ http://www2.mmm.ucar.edu/mm5/workshop/ws03/sessionJ1/Klausmann.pdf [bare URL PDF]
  3. ^ Dudhia, Jimy (June 2005). MM5 Version 3.7 (The Final Version). WRF/MM5 Users' Workshop – June 2005. Boulder, Colorado: National Center for Atmospheric Research.
  4. ^ a b c d e f g h i "Chapter 1: Introduction". .mmm.ucar.edu. Retrieved 2022-04-20.
  5. ^ http://www2.mmm.ucar.edu/mm5/documents/mm5-code-pdf/sec1.pdf [bare URL PDF]
  6. ^ a b c d "MM5 Community Model Homepage".
  7. ^ a b c d "MM5 Community Model Homepage". .mmm.ucar.edu. Retrieved 2022-04-20.
  8. ^ "MM5 OnLine Tutorial : LITTLE_R".
  9. ^ "MM5 OnLine Tutorial : RIP".
  10. ^ "Chapter 2: Getting Started".
  11. ^ a b c http://www2.mmm.ucar.edu/mm5/documents/mm5-code-pdf/sec2.pdf [bare URL PDF]
  12. ^ ww2.mmm.ucar.edu
  13. ^ http://www2.mmm.ucar.edu/mm5/documents/mm5-code-pdf/sec5.pdf [bare URL PDF]
  14. ^ "SUNY Stony Brook MM5 Mesoscale Forecasts for 2000030612". cheget.msrc.sunysb.edu. Archived from the original on 6 March 2000. Retrieved 6 June 2022.
  15. ^ "Real-Time Mm5 Forecasts". www.atmos.umd.edu. Archived from the original on 5 October 2002. Retrieved 6 June 2022.
  16. ^ "University of Wisconsin MM5 Real Time Forecast and Forecast Sensitivity Page". helios.aos.wisc.edu. Archived from the original on 9 March 2001. Retrieved 6 June 2022.
  17. ^ "Archived copy". Archived from the original on 2008-06-13. Retrieved 2008-06-25.{{cite web}}: CS1 maint: archived copy as title (link)
  18. ^ "Archived copy". Archived from the original on 2008-06-13. Retrieved 2008-06-29.{{cite web}}: CS1 maint: archived copy as title (link)
  19. ^ "Echam5-Mm5".
  20. ^ "Polar Meteorology Group Home Page". Archived from the original on 2008-06-07. Retrieved 2008-06-29.
  21. ^ a b c "MM5 Community Model Homepage".

External links

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