HIRLAM

Use of the Hirlam NWP Model

at Met Éireann (Irish Meteorological Service)

(James Hamilton -- Met Éireann)

COMPUTER SYSTEM and VERSIONS of HIRLAM

IBM RS/6000 SP : 9-nodes each with 4-CPU’s

• Operational Hirlam : 438x284 grid pts; 31-levels

• Nested Hirlam : 222x210 grid pts; 40-levels

LINUX PC : Twin Xeon Processors [2.0Ghz]

• Backup Hirlam : 218x144; 31-levels

LINUX PC : Twin Xeon Processors [500Mhz]

• Hourly Hirlam : 97x98 grid pts; 24-levels

LINUX Cluster : Nine Twin Xenon Processors [3.2GHz]

•Operational Hirlam : Test mode

OPERATIONAL HIRLAM … IBM RS/6000 SP

HIRLAM 5.0.1 with 3DVAR

• 3-Hour assimilation cycle with 48-hour forecasts every 6-hours

• Rotated lat/long 0.15x0.15 grid with 438x284 grid points

• Hybrid [eta] coordinates with 31-levels

• CBR vertical diffusion scheme; Sundqvist condensation scheme

• STRACO cloud scheme; Savijarvi radiation scheme

• Digital filter initialisation

• Two time-level Semi-Lagrangian semi-implicit scheme

• Use of ‘frame’ boundaries from ECMWF

BACKUP HIRLAM … LINUX-PC [Dual 2.0Ghz CPU]

HIRLAM 4.3.5 with OI-Analysis

• 3-Hour assimilation cycle with 48-hour forecasts every 6-hours

• Rotated lat/long 0.30x0.30 grid with 218x144 grid points

• Hybrid [eta] coordinates with 31-levels

SAME AREA AS OPERATIONAL HIRLAM

NESTED HIRLAM … IBM RS/6000 SP

HIRLAM 6.0.0 with 3DVAR

• 3-Hour assimilation cycle with 24-hour forecasts every 6-hours

• Model runs at intermediate hours … 03Z, 09Z, 15Z, 21Z

• Rotated lat/long 0.12x0.12 grid with 222x210 grid points

• Hybrid [eta] coordinates with 40-levels

• Kain-Fritsch/Rasch-Kristjansson convection/condensation scheme

• ISBA surface scheme

• Output post-processed with MOS

HOURLY HIRLAM ... LINUX-PC [Dual 500Mhz CPU]

HIRLAM 4.3 with OI Analysis

• Hourly assimilation cycle with hourly analysis and 3-hour forecast

• Rotated lat/long 0.15x0.15 grid with 97x98 grid points

• Hybrid [eta] coordinates with 24-levels

• Analysis shown on public web-site

OPERATIONAL USES of HIRLAM

General Forecasting

• Forecast guidance out to 48-hours

WAM wave model

• Forecast 10-metre winds used to drive model

Roadice Prediction System

• Forecast parameters are used as first guess for [human] forecaster

SATREP

• Overlay on satellite plots [ZAMG SATREP analysis scheme]

RESEARCH ACTIVITIES

Better Specification of B.C.’s for NWP models

Operational Implementation of Nested System

Regional Climate Analysis Modelling & Prediction Centre

Community Climate Change Consortium for Ireland

[RCAMPC and C4I]

EXPERIMENTS with LINUX CLUSTER …

Purchased small experimental Linux-Cluster

• Dell PowerEdge 1750 Twin Xeon nodes – rack mounted

• 1 x Master node [2.8GHz, 4Gbytes]

• 9 x Compute nodes [3.2GHz, 2Gbytes]

• Compute nodes in 3x3 2-dimensional torus [Dolphin cards]

• RedHat ES-3/WS-3; PGI compilers; Intel compilers

• Scali MPI connect, Scali TCP connect, Scali Manage

• Original cluster had 6-nodes : upgraded to 9-nodes

EXPERIMENTS with LINUX CLUSTER …

Running Operational Hirlam on Cluster [9-node]

• Hirlam 5.0.1 with 3DVAR – identical to operational system

• Forecast takes 62 mins on IBM/SP; 71 mins on cluster

• 3DVAR takes 15 mins on IBM/SP; 9 mins on cluster

• Full run takes 77 mins on IBM/SP; 80mins on cluster

• Therefore … 9-node cluster is as fast as IBM/SP

Experience with Cluster Generally Positive

FUTURE PLANS for CLUSTER ….

Investigate Use of Intel Compilers and Libraries

• Should be faster for running Hirlam

Use Cluster as test-bed to implement latest Hirlam 6.4

Use Cluster to prepare benchmark for new mainframe

Replace Mainframe end of 2006 / start of 2007

FUTURE PLANS …

Investigate Options to Replace Mainframe in 2006

Get Hirlam 6.4 Running on Cluster

Investigate MOS/Neural-Nets for Post-Processing

Use Hirlam as input to Point Data-Base

Thank You