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= Unified Model =

The Met Office Unified Model (UM) is the name given to the suite of numerical modelling software developed and used at the Met Office. The UM modelling software is designed so that the model can be run in atmosphere-only (global or limited area), ocean-only or in coupled atmosphere-ocean mode. The Unified Model is used by the [http://www.metoffice.gov.uk UK Met Office] for operational numerical weather prediction and by the [http://www.metoffice.gov.uk/climate-change/resources/hadley Hadley Centre for Climate Prediction and Research] to simulate and predict the Earth's climate.

== UM versions ==

The UM undergoes significant changes as new scientific enhancements are introduced or new features are added and so the [http://www.metoffice.gov.uk Met Office] release new versions regularly (approx. 3-4 times a year). NCAS-CMS only supports a subset of the versions released.

See [http://puma.nerc.ac.uk/trac/UM/wiki list of supported UM versions and platforms] on the [http://puma.nerc.ac.uk/trac/UM/wiki UM Trac].

All documentation relating to each UM version, including the UM User Guides, is available in the [http://cms.ncas.ac.uk/wiki/Docs/MetOfficeDocs Met Office Documentation] part of this website. A password is required in order to access the majority of the documentation.

== UM Configurations ==

In order to run the climate model, users need to have access to a set of files that will enable them to run a particular scientific version of the climate model (describing exactly the physical and dynamical choices within the UM system).  2 climate model 'families' (HadGEM2 and HadGEM3) are routinely being used and actively developed for climate research by the Met Office Hadley Centre.  These models differ very significantly in terms of their numerical and physical formulation. The Met Office have released several configurations of these models and NCAS-CMS have ported these "standard" configurations to the National HPC HECToR. 

See [wiki:UM/Configurations UM Configurations] page for full details.

== Source Code ==

The UM Fortran source code is available to to view via the [https://puma.nerc.ac.uk/trac/UM/browser UM Trac Code Browser] or alternatively, the UM source code has been converted into a hyperlinked website. 

See [wiki:/UM/CodeBrowsers UM Source Code Browsers]

== Running the UM ==

The UM is a complex software sytem so a new user should read the documentation available on this web site and complete the [wiki:UmTraining UM training] provided by NCAS.

The UM software needs to be properly installed so that the scripts, tools, code and files for running an experiment are available. NCAS installs and maintains the supported UM versions on the UK national high performance computers. All NCAS researchers can use the UM on these services, details of getting accounts can be found on this web site. [ [wiki:FAQ_T3_F6 more information .... ] ]

UM experiments need input files to run and they create output files for diagnosing the experiment. NCAS has created a set of tools and utilities, to supplement the standard ones from the UK Met Office, to support the creation, manipulation and use of these UM files. [ [wiki:ToolsAndUtilities/UmFileTools more information ....] ]

Detailed documentation for running a UM experiment on the UK high performance computers can be found [wiki:UM/RunningUMOnHector here] .