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Unified Model Developments 2005 for EWGLAM/SRNWP Annual Meeting 2005

This presentation covers the latest developments and future plans in NWP models, including global and regional ensembles, supercomputers for NWP and climate research, systematic errors, and planned global changes for 2005-6. It also discusses the introduction of ensembles, including the Global Ensemble and North Atlantic/European Ensemble. The impact of systematic errors, changes in tropical precipitation, and planned NAE model developments are highlighted.

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Unified Model Developments 2005 for EWGLAM/SRNWP Annual Meeting 2005

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  1. Unified Model Developments 2005 for EWGLAM/SRNWP Annual Meeting 2005 3-5 October 2005, Ljubljana, Slovenia Mike Bush NWP

  2. Current UM configurations and future plans • Global model • Global and regional ensembles • NAE (North-Atlantic European) model • CAMMS and Africa model • HRTM • U.K 4km model

  3. Current NWP Model Configurations Global 60Km 38 levels NAE 12Km UK Mes 12Km UK 4km Trial ensemble Global 90km & Regional 24km CAMMs Africa 20km

  4. 2006: NWP Model Configurations Global 40Km 70 levels NAE 12Km UK 4km Trial ensemble Global 90km & Regional 24km CAMMs Africa 20km

  5. Supercomputers for NWP and Climate • NEC SX6 Operational since April 2004 • Twin 15 node system • 1.86 TFlop • April 2005 Upgrade • Additional 4 SX6 nodes • Plus 16 node NEC SX8 • 4.08 TFlop • Will allow the running of ensembles and increased resolution models including those used in climate research

  6. Current UM configurations and future plans • Global model • Global and regional ensembles • NAE (North-Atlantic European) model • CAMMS and Africa model • HRTM • U.K 4km model

  7. Global model developments • G33 5th October 2004 • Introduction of 4D-VAR. • G34 18th January 2005 • HadGEM physics upgrade • G35 8th February 2005 • Data Assimilation upgrade. • G36 14th June 2005 • DA and satellite upgrade. • G37 17th August 2005 • Implementation of a soil moisture nudging scheme.

  8. Global model cycle G34 – 18th Jan 2005 • Introduction of HadGEM physics • 3C Large Scale precipitation scheme (replacing 3B). • 8B Boundary Layer (replacing 8A). • Increase in Saharan surface albedos. • Benefits • Improved tropical performance • Increased (Reduced) Precipitation over land (Ocean). • Improved tropical circulation & winds. • Reduced low cloud (Iraq); Improved 1.5m T. • Improved surface T and circulation over Sahara. • Drawbacks • Increase existing warm bias in extratropics

  9. Systematic Errors in Tropical Precipitation

  10. Impact of 30min CAPE closure

  11. Global model cycle G37 – 17th Aug 2005 • Implementation of a soil moisture nudging scheme • Replaces the weekly resetting to climatology. • Errors in the 6-hour forecasts of screen temperature and humidity are used to infer corrections to the soil moisture field. • The scheme derives these from the physics of the land-surface model. • Summer trials showed improvements to surface and boundary-layer temperature forecasts. • Winter results were close to neutral.

  12. 2005Q3 2005Q4 2006Q1 2006Q2 Planned Global Changes (2005-6) • 4D-Var upgrade • better incremental physics, less obs thinning (ATOVS) • Increased Resolution (phase 1) • ~ 40 km, ~50 level • Better use of Satellite Data • SSMI-S, Microwave Cloudy radiances, MSG winds (Meteosat 7 -> 8) • Convection and Boundary Layer tuning • Increased Resolution (phase 2) • -> 70 levels 1 2 3 4 5

  13. Current UM configurations and future plans • Global model • Global and regional ensembles • NAE (North-Atlantic European) model • CAMMS and Africa model • HRTM • U.K 4km model

  14. Introduction of Ensembles • GEPS1 14th June 2005 • 24 member Global Ensemble at N144 (~90km) resolution twice per day (00Z, 12Z) to T+72 hours. • ETKF perturbations, stochastic physics • Initially there will be a one year trial in which forecasters can view output on the internal web • EPS1 17th August 2005 • 24 member North Atlantic/European Ensemble at 24km resolution twice per day (06Z, 18Z) to T+36 hours • IC perturbations taken directly from global model • Nested within global ensemble for LBCs • Plans to engage in multi-model ensembles with USA and Canada (THORPEX). Proof of concept by March 2006

  15. MOGREPS Spaghetti chart

  16. MOGREPS Probability map

  17. Current UM configurations and future plans • Global model • Global and regional ensembles • NAE (North-Atlantic European) model • CAMMS and Africa model • HRTM • U.K 4km model

  18. NAE model developments • E5 18th January 2005 • Change in domain • E6 22nd February 2005 • Horizontal resolution increased from 20km to 12km. • E7 14th June 2005 • New surface soil moisture analysis. • E8 17th August 2005 • Removal of truncation of vertical modes in VAR from 21 to full 38.

  19. 2005Q3 2005Q4 2006Q1 2006Q2 Planned NAE Changes (2005-6) • Use of modified Global covariances • Introduction of HadGEM physics • Introduction of 4D-Var • More new satellite data • Full resolution AMSU-B, Assimilation of GPS data, MODIS winds etc. • Increased Resolution • 70 levels 1 2 3 4 5

  20. NAE model cycle E9 – 12th Oct 2005 • Use of modified Global covariances • Generated using the NMC method • Replaces the use of U.K Mes covariances. • Global covariances fit less closely to obs but the horizontal length scales are longer. • Large improvements to the performance of the model • Ideally would use NAE covariances, but forecast differences are dominated by the use of different lateral boundary conditions.

  21. NAE PMSL bias and RMSE

  22. NAE 10m wind speed bias and RMS Vector Error

  23. NAE Screen level temperature bias and RMSE

  24. NAE performance issues • The NAE model (12km resolution) covers the North Atlantic – it is unusual for a LAM to cover such a large sea area. • Rationale is that by modelling the North Atlantic at high resolution, forecasts for Europe will be better than if a smaller domain over Europe was chosen. • Choice of covariances of crucial importance to the model performance (must do a good job over both sea and land). • The Global model does a good job at synoptic scales and the NAE has struggled to do a better job than it at these scales (lateral boundary conditions don’t help either). • LAM’s are good at adding detail to Global model output.

  25. Current UM configurations and future plans • Global model • Global and regional ensembles • NAE (North-Atlantic European) model • CAMMS and Africa model • HRTM • U.K 4km model

  26. Southern Asia CAMM Current Operational CAMM configurations • Southern Asia (17km) • Falklands (12km)

  27. Bay of Bengal CAMM (Tsunami Aid effort) Bay of Bengal CAMM 17km 00z and 12z  T+48 320x240 38 levels Requested Tuesday 4th Jan Delivered to Operations Thursday 6th Jan Operational Monday 10th Jan

  28. USA CAMM: Hurricane Rita Global Model (60km) USA CAMM (17km) 70kt 10m wind, 962mb • Global model central pressure: 992mb • USA CAMM central pressure: 972mb • NHC advisory (estimate): 929mb

  29. USA CAMM: Hurricane Rita Global Model (60km) USA CAMM (17km) 70kt 10m wind, 962mb • USA CAMM has track slightly west of the Global model

  30. African LAM • Met Office vision: increased focus on assisting developing countries / disaster mitigation • Introduced into the Operational Suite on 13th April 2005 • Currently one forecast a day (00Z) to T+48 • 20km horizontal resolution • Contains HadGEM physics • Introduction of data assimilation (6 hour cycle) in Winter 2005/2006 • Increased vertical resolution (2006)

  31. African LAM

  32. Africa LAM rainfall on 16th April 2005 TRMM =Tropical Rainfall Measurement Mission satellite

  33. Current UM configurations and future plans • Global model • Global and regional ensembles • NAE (North-Atlantic European) model • CAMMS and Africa model • HRTM • U.K 4km model

  34. HRTM Model High Resolution Trial Model • Centred Over the Chilbolton Radar (High Resolution observational data for evaluation and validation) • HRTM 4 km nested in operational UK-MES. Used for research and to provide lateral boundary conditions to the HRTM 1 km • Over two years in development • Basis for the now operational UK4 model • Continued development

  35. HRTM Scientific Options • Dynamics: Non hydrostatic, Semi-Lagrangian advection and Semi-Implicit time integration (New Dynamics). • Boundary Layer: 1st order non-local K scheme with explicit entrainment. • Horizontal diffusion: Del-4 operator in U, V, Q, and Theta. • Microphysics: Mixed phase scheme + 3D advection of precipitation products. • Radiation: Two stream scheme with 5 spectral bands for short wave and 5 for long wave

  36. HRTM Scientific Options (Convection) • Deep convection: explicitly resolved • Shallow convection: parametrised • Solution based on the operational mass flux scheme with CAPE closure • CAPE reduction timescale dependent on CAPE. • Large values of CAPE: CAPE reduction timescale increases. Activity of convection scheme reduced and deep convection is explicitly resolved. • Small CAPE: Minimum value of CAPE timescale fixed. Shallow convection processes are taken into account. Delay in the onset of convection as the convection scheme is made less active.

  37. HRTM Scientific Options (Convection) Function chosen: linear with CAPE for large CAPE values and exponential for small CAPE values min/CAPEmin governs the asymptotic slope of the function and is related to the limit to the cloud base mass flux min governs activity of convection scheme for small CAPE values

  38. HRTM Tests: Effect of lateral boundary updating frequency 60 minutes 30 minutes 15 minutes Chosen frequency: 30 minutes

  39. Current UM configurations and future plans • Global model • Global and regional ensembles • NAE (North-Atlantic European) model • CAMMS and Africa model • HRTM • U.K 4km model

  40. UK4 Model • 320 rows by 288 columns • 0.036 degrees gridlength (4 km aprox.) • 38 Levels (13 in boundary layer) • 100 seconds timestep • Same scientific settings as HRTM

  41. UK4 Model (Pre-operational tests) Testing strategy 21 Case studies: • Coverage of all main weather regimes, although biased towards severe weather events. • Nested in UK-MES (12 km) Continuous trial • 1st of March to 1st of April 2005, at 00 and 12 UTC • Varied weather through the period • Nested in operational NAE (12 km)

  42. Case study 11/08/04 18Z Organised convection ■Banded structure in the 6hr ppn accumulation compares well with radar.

  43. Case study 11/08/04 18Z Organised convection ■ However the banded structure persists in the 24hr accumulation while the radar image is smooth. ■Better agreement when averaged to a 12km grid.

  44. UK4 Model (Pre-operational tests) “Borders Grid Point Storm” (03/08/2004 00Z, T+13)

  45. UK4 Model (Pre-operational tests)

  46. UK4 Model Pre-operational tests summary • Very robust • Small structure of precipitation too persistent • Unrealistically high single row/point precipitation rates (grid point storms) • Better forecast of fog than coarser resolution operational models • Negative cloud bias (operational models use a cloud enhancement scheme) • Diurnal cycle in screen temperature bias due to cloud bias • PMSL errors strongly linked to errors in the driving model

  47. Introduction into operations of the UK4 Model • U4.01 13th April 2005 • One forecast per day to T+36 at 00Z • U4.02 17th June 2005 • Extra T+36 forecast at 12Z added • No operational failures. • Negative cloud bias confirmed. • Feedback from forecasters: • Positive overall. • Number of false alarms of heavy precipitation events. • Excessive precipitation rates and organisation of ppn. • Too much light precipitation was observed, as statistics for longer periods were available.

  48. UK4 Operational (North Yorkshire floods) Rye Valley floods. 19/06/2005 Good guidance at T+17 in intensities, time and location But false alarm over South Wales at T+9

  49. MES 12Z 6 hr rainfall Radar 12Z 6 hr rainfall 4 km 12Z avg 6 hr rainfall 12-18Z 12-18Z 12-18Z 19 June 2005 Flash flooding caused by thunderstorms over North Yorkshire Error scale (km) Rainfall threshold (mm)

  50. UK4 model cycle U4.03 – 12th Oct 2005 • Upgrade of convection scheme to current operational version. Keeping the CAPE dependent CAPE closure modification. • Substitute horizontal diffusion of moisture by targeted diffusion of moisture. • Include cloud enhancement scheme. • Tune microphysics parameters to reduce excessive light precipitation

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