Unified Model Developments 2002 Clive Wilson NWP Met Office

Outline Configurations & Users Global and UK Mesoscale Changes Regional European Model New supercomputer Plans

Operational Versions & External Users Global 38 levels, N216= 432x325 (~60km) UK Mesoscale 38 levels, 0.11 deg (12km) Stratospheric 42 levels (~1.3km @ 100-1hpa), N48=96x73 (~300km) Crisis models (LAMS) Middle East, Former Yugoslavia,SW Asia External CGAM UK, ICM Warsaw, Thai Met Service, New Zealand, DNMI

Changes Global UK Mesoscale G26 16 Oct 3dvar upgrade Increase Observation errors for AMVs Revise thinning of ATOVS to give preference to microwave-clear over IR-clear Use of fractional sea-ice in ATOVS processing G27 7 August 2002 New Dynamics and HadAM4 G28 1 Oct Introduce NOAA17 UK Mesoscale G27 7 August 2002 New Dynamics

*Already operational in Mesoscale Model

Expected benefits of New Dynamics Non-hydrostatic capability – ability to increase resolution in UK area. Improved stability and accuracy - less noise in forecasts Improved physics for global model - improved coupling to dynamics. Unify physics between global and UK area - Better boundary conditions. Better coupling with 3D-Var which was designed around new grid.

New Dynamics levels

Bars show the %change in RMSE (NDHadAM4 - OP/OP) for the components, which make up the NWP index. Verification is against observations. Blue signifies Northern Hemisphere, red the Tropics and Green is the Southern Hemisphere. A negative value implies NDHadAM4 is an improvement over OP.

Typhoon Phanfone 18 August 2002

Screen temperature OP ND mean forecast range forecast range rms Shadow suite (16/1-4/2), all stations OP ND mean forecast range forecast range rms 0 12 24 36

10-metre wind OP ND mean speed rms vector 0 12 24 36 Shadow suite (16/1-4/2), all UK stations OP ND mean speed rms vector 0 12 24 36

Relative Humidity OP ND mean forecast range rms 0 12 24 36 Shadow suite (16/1-4/2), all stations OP ND mean forecast range rms 0 12 24 36

Visibility Shadow suite (6/12-4/2), all stations

Rainfall (skill) Shadow suite (6/12-28/1) v Nimrod 6-hourly accumulations

Rainfall (bias) Shadow suite (6/12-28/1) v Nimrod 6-hourly accumulations

Strong summer convection

ND OP T+0 French Storm Vt 12Z 27/12/1999 T+72

OP ND T+0 Danish Storm Vt 12Z 03/12/1999 T+24

Reduced Noise in New Dynamics

New Dynamics Summary Benefits Problems Reduced NH RMSE in summer and at early FC ranges in winter Deeper extratropical cyclones Reduced temperature biases Improved stratospheric circulation statistics (eddy temperature fluxes) Reduced noise in ND forecasts. Improved radiative balance - OLR Tropical upper level wind RMSE too large (~6-10%) SH T+24 wind RMSE too large (vs analysis) - corrections ready Grid point storms at N216. Tuning of orographic and BL drag and diffusion still required. Low cloud in UK mesoscale Poor initial precipitation in UK Mes

New Regional European model Opportunity to reorganise Operational suite New dynamics model formulation (August 2002) Better Global performance but double cost 2X number of processors to keep to delivery time Mesoscale ~same as current relatively more efficient than global Remove duplication of Global Preliminary/Main runs

Resources Make full use of operational time & processors Processors global 288, UKmes 108  factor of 2.8 Release duplicate Prelim/main analysis +2 day forecast (=40min) 60min slot (=20 min gap + “duplicate time”) ~5X UKmes cost

Proposed Domain 548 320 New Euro Mes 20km resolution Current UK mesoscale 320 New Euro Mes 20km resolution

Current Operational Schedule 00/12 +1:50 2 Days Prelim Run P 00/12 Boundary Forcing +2:40 2 Days +3:00 Main Run 6 Days G Ocean, wave, surge +4:50 2 Days +7:50 Prelim Run P

Proposed Operational Schedule 2 Days Main Run part 1 00/12 +1:50 00/12 Continued Main Run Days 2-6 +3:40 +3:00 E 2 Days Euro Run Boundary Forcing 2 Days +2:40 Ocean, wave, surge +4:50

Estimated Global worsening 250hPa winds

Estimated effect on Global Index

Timetable 5 November - Merge Prelim/Main model +digital filter intitialisation instead of incremental analysis update but leave split of run until next year 12 Nov -Forecast only European Model introduced Post November -products and downstream use developed 14 Jan - basic data assimilation 25 March- model & DA upgrade June 03 - Declare Euromodel operational (high risk -Exeter transition)

New supercomputer need Improve NWP systems: Satellite data volumes New Dynamics 4D-VAR Higher resolutions Very fine resolution mesoscale (~2km) European Mesoscale model Short range Ensembles Operational Suite creaking at the seams

What are we getting? Initially - NEC SX-6 30 nodes Each node has 8 CPUs sharing 64Gb of memory Each CPU is equivalent to approx 30 T3E CPUs Overall performance: 6x T3E’s for “performance work” > 6x T3E’s for “throughput work”

And in the future In 2005 - joined by SX-6 successor: 15 nodes Each CPU twice as powerful Overall performance 12.5x T3Es for “performance work” >12.5x T3Es for “throughput work”

Benchmark Results (N324L50)

The Bits IXS Met Office Networks FibreChannel NODE (8 CPUs) IXS (Interconnect) IXS NODE (8 CPUs) Gigabit Ethernet FC Switch Mirrored filesystems User filesystems FibreChannel Front End 12xIA64 Met Office Networks

Timetable Installation Bracknell SX-6 1 node system Upgrade: 4 nodes Front end Move to Exeter Exeter SX-6(B) 15 node system Exeter SX-6(A) Acceptance tests Sep 02 Oct 02 Nov 02 Dec 02 Jan 03 Feb 03 Mar 03 Apr 03 May 03 Jun 03 Jul 03 Aug 03 Sep 03 Oct 03 Nov 03 Dec 03 Date T3E-A Move to Exeter 02/09-06/10 T3E-B 17/06-22/07

Plans 2002- 2003 November UK Mes DA-improved covariances December Global model & DA January New Dynamics in Stratospheric model Data assimilation in Euro model Feb-March -Global, UK mes & Euro model+DA upgrades Transition to Exeter Moratorium May 03 - October 03

Future Plans 4dVar Increased resolution Physics Practicable global synoptic scale ready for test on new computer end 03 Inclusion physical processes 04 operational early(?) 2004 Increased resolution 40km , 50L Global; 10km , 50L Euro mesoscale Physics new gravity wave drag new convection new cloud (prognostic cloud and condensate)