The Unified Model is the name given to the suite of atmospheric and oceanic numerical modelling software developed and used at the Met Office. The formulation of the model supports global and regional domains and is applicable to a wide range of temporal and spatial scales that allow it to be used for both numerical weather prediction and climate modelling as well as a variety of related research activities. The Unified Model was introduced into operational service in 1991. Since then, both its formulation and capabilities have been substantially enhanced.

Data from the operational NWP (Numerical Weather Prediction) output from the Met Office Unified Model. These data are from both the Global and the North Atlantic European (NAE) part of the model. The NAE model runs on a grid centred around the UK. Analyses and intermediate forecast steps are stored to give an hourly time resolution for 6 hours following each analysis time-step. This archive only holds data to January 2012. A new NWP archive is being populated with data from January 2012. The dataset starts on 23 October 2000, and is ongoing. Around 1.6Gb of data are stored for each day.

Analysis fields at 0,6,12,18Z are stored, along with all of the forecast fields from 1-6 hours from each analysis time.

Mesoscale : lb[a,f][m,p]yyyymmddhh_STASHCODE_fh.pp

Global: ag[a,f][m,p]yyyymmddhh_STASHCODE_fh.pp

where yyyymmddhh is the year, month,day and assimilation time, STASHCODE is the STASHMASTER parameter code, fh is the forecast timestep (from the assimilation time), and pp indicates that the files are in binary "pp" format.

The directory structure has also been changed to bring it in line with the BADC ECMWF holdings. The mesoscale files and global data are now stored under:

/badc/ukmo-um/data/meso/lb/a[m,p] for the analysis fields

/badc/ukmo-um/data/meso/lb/f[m,p] for the forecast fields

/badc/ukmo-um/data/global/ag/a[m,p] for the analysis fields

/badc/ukmo-um/data/global/ag/f[m,p] for the forecast fields

Pre-2004 data are still available in the old format under /badc/ukmo-um/data/mesocale/[sm,mm] and /badc/ukmo-um/data/global/[mg,sg], although these will be phased out as the data are archived in the newer format.