The Unified Model (UM) is a numerical model of the atmosphere used for both weather and climate applications. It is in continuous development by the Met Office and its partners, adding state of the art understanding of atmospheric processes to new releases.
Seamless modelling, whereby a single model family can be used for prediction across a range of timescales, has been at the heart of the Met Office strategy for weather and climate prediction since 1990.
The UM applies this seamless modelling approach, which means that the same dynamical core and, where possible, the same parameterization schemes are used across a broad range of spatial and temporal scales on a traceable frame work. The model is suitable for numerical weather prediction (NWP), seasonal forecasting and climate modelling with forecast times ranging from a few days to hundreds of years. Furthermore, the UM can be used both as a global and a regional model.
The model's dynamical core solves the compressible non-hydrostatic equations of motion with semi-lagrangian advection and semi-implicit time stepping. Sub-grid scale processes such as convection, boundary layer turbulence, radiation, cloud, microphysics and orographic drag are represented by parameterizations. The model uses a grid point discretization on a latitude-longitude grid system with a rotated pole.
The UM is available for use outside the Met Office through a licensing agreement aimed at meeting the needs of the user. A number of research organisations and national meteorological services use the UM in collaboration with the Met Office to undertake basic atmospheric process research, produce forecasts, develop the UM code and build and evaluate earth system models.
As part of the Joint Weather and Climate Research Program (JWCRP) between the Met Office and NERC, the UM is also available for use on the MONSooN High Performance Computing facility to improve collaboration between scientists funded by the two organisations. MONSooN is a shared development platform which provides users with the technical knowledge as well as the ability to run experiments with standard UM configurations. For more information about MONSooN visit the JWCRP page.
More information on the use of the UM, as well as the opportunities and support available for collaboration can be found on the Unified Model collaboration page. For access to model output contact the Met Office enquiries team.
Different systems of the UM are available, customized for resolution and application. The systems used at the Met Office are described in the pages linked below.
Last updated: 7 September 2016