The Met Office NWP System & The UM

1. The Met Office NWP System & The UM Glenn Greed, NM (Met R&D) Stuart Moore, NM (Met R&D) 01 June 2007

2. NWP system overview

3. 2007 Operational Forecast Systems UK 4km 38 levels Regional 12km 38 levels +EPS 24member,24km Global 40km 50 levels +EPS 24member,90km http://www.metoffice.gov.uk/research/nwp/numerical/operational

4. Met Office NWP System (Global and Regional) 4DVAR Data Assimilation OBS Unified Model Forecast Forecast productsand guidance

5. Improving the models Each NWP model is run by production within what is known as the critical suite. (Other models include wave models, SSFM etc) Future upgrades undergo final testing in a Parallel suite, check no problems in the downstream products. (Mirror of critical suite.) But before getting to this stage within NWP upgrades are tested in our own trials and the expected benefits are presented to WGOS to get the go ahead. OBS VAR Model

6. Unified Model

7. What can the UM do? • Cannot process observations – OPS/ODB does that • Cannot assimilate observations – VAR does that • Cannot objectively verify results – VER & SBV do that • Cannot store/retrieve data – MASS does that • Cannot control all the above – SCS does that • Cannot post-process results – PV-WAVE and Metview do that • Cannot analyse results – you do that

8. The Unified Model • Introduced in 1991 at Met Office (http://www.metoffice.gov.uk/research/nwp/numerical/unified_model/) • The same modelling system is used for all applications from climate scale to kilometre scale (http://www.metoffice.gov.uk/research/nwp/numerical/unified_model/new_dynamics.html) • Covers global, regional, atmosphere and ocean • Synergy between climate modelling, seasonal forecasting and NWP. • Research in each area can benefit the other.

9. Climate modelling: input into IPCC reports (Coupled Atmosphere-Ocean models) Seasonal forecasting: For commercial and business customers NWP: Public Weather Service WAFC, Commercial …… The Unified Model The same model formulation is used for all models from climate scale to mesoscale

10. The Unified Model The Unified Model is available for use under licence by: National Met Services*, Research institutes* and Commercial partners* • Validated on: • Cray T3E, NEC SX8, IBM p690, SGI Origin 3000, Linux and Linux cluster. • Delivered with instructions and documentation. • Collaboration with: • Norwegian Met (SGI/IBM);South African Weather Service (NEC); Australian Bureau of Meteorology (NEC); NIWA New Zealand (T3E) and UK Universities (IBM/Cray). * Subject to terms and conditions

11. Using the UM….. • Job set up via the UMUI • control over job resources • control over science choices • control over job output choices • User documentation available for, • the UM • the UMUI • and various technical and scientific components • some Help available within the UMUI itself

12. Reconfiguration • Standalone program which modifies start dumps • Add/subtract fields from dump • For atmosphere only: • Interpolate to new domain or resolution • Supply ancillary fields Land Sea Mask,ozone, orography, soil/veg, SSTs etc. Boundary conditions for a model. • Supply ensemble perturbations • Transplant prognostic fields

13. Examining output (utilities) UM diagnostic output on the NEC is a ‘fieldsfile’ • pumf useful for checking header info in fieldsfiles or a dumps • cumf useful for checking bit-comparibility of two files • xconv can visualise dumps, fieldsfiles, ancils • convpp & ieee convert fieldsfiles (TX-7) to ppfiles/GRIB files (Linux) - eventually • Once there – PV-WAVE or MetView or any other suitable graphics package

14. Conclusions • The UM is a very powerful, very well-developed tool for simulating the atmosphere and ocean • Used at Met Office in Operations and Research • Supported by a variety of pre- and post-processors • UM runs are defined through a user-friendly UI • You need to know how to run it • The UM is to be replaced by the next generation version FLUME…………

15. Questions & Answers