Page 1© Crown copyright 2004 Unified Model Developments 2005 for EWGLAM/SRNWP Annual Meeting 2005 3-5 October 2005, Ljubljana, Slovenia Mike Bush NWP.

© Crown copyright 2004 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

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

© Crown copyright 2004 Global model cycle G34 – 18 th 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 o Increased (Reduced) Precipitation over land (Ocean). o 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

© Crown copyright 2004 Global model cycle G37 – 17 th 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.

© Crown copyright 2004 Planned Global Changes (2005-6) 1.4D-Var upgrade better incremental physics, less obs thinning (ATOVS) 2.Increased Resolution (phase 1) ~ 40 km, ~50 level 3.Better use of Satellite Data SSMI-S, Microwave Cloudy radiances, MSG winds (Meteosat 7 -> 8) 4.Convection and Boundary Layer tuning 5.Increased Resolution (phase 2) -> 70 levels 2005Q3 2005Q4 2006Q1 2006Q2 1 2 3 4 5

© Crown copyright 2004 Introduction of Ensembles 1.GEPS1 14 th 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 2.EPS1 17 th 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 3.Plans to engage in multi-model ensembles with USA and Canada (THORPEX). Proof of concept by March 2006

© Crown copyright 2004 NAE model developments  E5 18 th January 2005  Change in domain  E6 22 nd February 2005  Horizontal resolution increased from 20km to 12km.  E7 14 th June 2005  New surface soil moisture analysis.  E8 17 th August 2005  Removal of truncation of vertical modes in VAR from 21 to full 38.

© Crown copyright 2004 Planned NAE Changes (2005-6) 1.Use of modified Global covariances 2.Introduction of HadGEM physics 3.Introduction of 4D-Var 4.More new satellite data Full resolution AMSU-B, Assimilation of GPS data, MODIS winds etc. 5.Increased Resolution 70 levels 2005Q3 2005Q4 2006Q1 2006Q2 1 2 3 4 5

© Crown copyright 2004 NAE model cycle E9 – 12 th 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.

© Crown copyright 2004 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.

© Crown copyright 2004 Bay of Bengal CAMM (Tsunami Aid effort) Bay of Bengal CAMM 17km 00z and 12z  T+48 320x240 38 levels Requested Tuesday 4 th Jan Delivered to Operations Thursday 6 th Jan Operational Monday 10 th Jan

© Crown copyright 2004 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

© Crown copyright 2004 African LAM  Met Office vision: increased focus on assisting developing countries / disaster mitigation  Introduced into the Operational Suite on 13 th 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)

© Crown copyright 2004 HRTM 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 High Resolution Trial Model

© Crown copyright 2004 HRTM Scientific Options  Dynamics: Non hydrostatic, Semi-Lagrangian advection and Semi-Implicit time integration (New Dynamics).  Boundary Layer: 1 st 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

© Crown copyright 2004 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.

© Crown copyright 2004 HRTM Scientific Options (Convection) Function chosen: linear with CAPE for large CAPE values and exponential for small CAPE values  min governs activity of convection scheme for small CAPE values  min / CAPE min governs the asymptotic slope of the function and is related to the limit to the cloud base mass flux

© Crown copyright 2004 UK4 Model (Pre-operational tests) 21 Case studies:  Coverage of all main weather regimes, although biased towards severe weather events.  Nested in UK-MES (12 km) Continuous trial  1 st of March to 1 st of April 2005, at 00 and 12 UTC  Varied weather through the period  Nested in operational NAE (12 km) Testing strategy

© Crown copyright 2004 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.

© Crown copyright 2004 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

© Crown copyright 2004 Introduction into operations of the UK4 Model  U4.01 13 th April 2005  One forecast per day to T+36 at 00Z  U4.02 17 th 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.

12-18Z Radar 12Z 6 hr rainfall MES 12Z 6 hr rainfall4 km 12Z avg 6 hr rainfall Error scale (km) Rainfall threshold (mm) 19 June 2005 Flash flooding caused by thunderstorms over North Yorkshire

© Crown copyright 2004 UK4 model cycle U4.03 – 12 th 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

© Crown copyright 2004 Planned UK4 changes December 2005:  Introduce 3D VAR assimilation system (plus Analysis Correction scheme for cloud and precipitation).  Introduce orographic wave drag parametrisation.  Introduce anthropogenic urban heat source.  Introduce daily initialisation of soil moisture 2006:  Increase vertical resolution.  Introduce seasonal variability in Leaf Area Index  Split urban tile type in rooftops and street canyons  Review convection scheme

Page 1© Crown copyright 2004 Unified Model Developments 2005 for EWGLAM/SRNWP Annual Meeting 2005 3-5 October 2005, Ljubljana, Slovenia Mike Bush NWP.

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Page 1© Crown copyright 2004 Unified Model Developments 2005 for EWGLAM/SRNWP Annual Meeting 2005 3-5 October 2005, Ljubljana, Slovenia Mike Bush NWP.

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Presentation on theme: "Page 1© Crown copyright 2004 Unified Model Developments 2005 for EWGLAM/SRNWP Annual Meeting 2005 3-5 October 2005, Ljubljana, Slovenia Mike Bush NWP."— Presentation transcript:

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