1. External Projects related to WG 6
COSMO Working Group 6: Reference Version and Implementation
Working Group Coordinator: Ulrich Schättler

2. Contents Interoperability
Priority Project POMPA: Performance On Massively Parallel Architectures
COSMO General Meeting 2010

3. Status of the Interoperability Programme
Ulrich Schättler DWD
Philipp Glatt MeteoSwiss

4. Idea of Interoperability
To support future collaborative effort in European Limited Area Modelling by:
Defining a standard output format
Providing software tools (adaptors) to convert LAM output to the standard format
Enabling European LAMs to run from appropriate alternative model fields
To display or use in NMHS post-processing system
To provide operational backup
COSMO General Meeting 2010

5. Plans for the Adaptor Fieldextra For Parameter List 1:
ps, psml, t2m, td2m, …
GME UM
ARPEGE
IFS
Fieldextra
Read (Write) Grib 2
and transform to
COSMO-Model grid:
only 2D fields
COSMO
UM_local
ALADIN
HIRLAM
COSMO General Meeting 2010

6. Plans for the Adaptor GFS? GSM? INT2LM For Parameter List 2:
u, v, w, t, p, qx, …
GME
ARPEGE
to be done
status unclear
GFS?
GSM?
INT2LM
Read (Write) Grib 2
and transform to
COSMO-Model grid:
2D fields, full atmosphere,
soil parameters
COSMO
ALADIN
HIRLAM
COSMO General Meeting 2010

7. lum2lm (Grib1): Temperature (lowest COSMO Level) from
GME
IFS UM
Aemet UM
DWD
COSMO General Meeting 2010

8. lum2lm (Grib1): PP from reference pressure (lowest level) from
GME
IFS UM
Aemet UM
DWD
COSMO General Meeting 2010

9. lum2lm (Grib1): Wind speed (lowest level) from
GME
IFS UM
Aemet UM
DWD
COSMO General Meeting 2010

10. Workshop in Reading
In December 2009, the “Interoperability Team” met in Reading for discussing last years work and do some planing for 2010.
The first 2 deliverables were finally agreed:
The Standard Format shall be the native grid and native parameters
Documentation supplied with the standard format should be the minimum required
Some Grib 2 Issues were discussed: There is a problem with coding the vertical coordinate / vertical grid of COSMO in Grib 2 (see tomorrows session on Postprocessing)
COSMO General Meeting 2010

11. Work in 2010 Vertical coordinate / vertical grid of the COSMO-Model
A COSMO-internal discussion about coding the vertical grid in Grib2 has been initiated early 2010
For the Gal-Chen height based hybrid coordinate it is possible to code the grid with typeOfLevel=118, the corresponding orography (as a 2D field) and vertical coordinate parameters
This is NOT possible for e.g. the SLEVE coordinate
The COSMO discussion led to a proposal to the WMO Commission for Basic Systems (IPET-DRC: Inter-Programme Expert Team on Data Representation and Codes). A new vertical coordinate type is proposed, where no vertical coordinate parameters together with a 2D field are given, but a full 3D field with the heights of every grid point is specified.
The proposal has been discussed also with Enrico Fucile (ECMWF)
COSMO General Meeting 2010

12. Work in 2010
grib_api
grib_api has been established at some COSMO centres to be the official Grib(2) library (DWD, MeteoSwiss, ARPA-SIM Bologna)
Work is in progress to improve performance on NEC machines (together with NEC, MeteoFrance and ECMWF)
It has been implemented in FieldExtra for reading and writing. FieldExtra therefore can now produce the parameters of the standard output format list directly
Work is in progress, to implement it into INT2LM
COSMO General Meeting 2010

13. Work in 2010 New Grib 2 test data set and documentation
A new Grib2 test data set, which has been produced by FieldExtra, has been provided. This still has the old (Grib1-style) coding of the vertical coordinate
No Grib2 test data has been provided with typeOfLevel=118, because this might not be the default case any more (if proposal is accepted)
No surface test data (according to the guidelines from the ET on Surface Aspects) has been provided up to now
The minimum required level documentation has not been updated according to the plans from last workshop
describe native grids
describe fields in the standard output list: what field is it, what does it represent in the generating model
COSMO General Meeting 2010

14.
COSMO General Meeting 2010

15.
COSMO General Meeting 2010

16. Priority Project POMPA Performance on Massively Parallel Architectures
(To be confirmed by STC)
Project Leader Oliver Fuhrer MeteoSwiss

17. Background: Future Computer Architectures
Computer architectures are about to change.
Multi-core, many-core systems are on their way.
Many people talk about General Purpose GPUs.
But first: Identify the problems of the COSMO-Model on existing machines!
NEC SX-9
8 Procs
IBM pwr6
256 procs
Computations Dynamics
729.59
570.44
Computations Physics
506.18
220.45
Communications
115.61
207.69
I/O
124.43
108.40
% of I/O and Comm. 15 25
COSMO General Meeting 2010

18. Investigations from Fraunhofer / SCAI on BlueGene with RAPS 4.1
Fraunhofer / SCAI investigated LM_RAPS_4.0 on IBM BlueGene
The RAPS code is not as optimized on NEC SX-9 as the current operational model is
Timings for COSMO-DE 421  461  50 grid points, dt=25 s
Modern architectures surely are more similar to BlueGene than they are to SX-9
There are problems in the I/O and the overall scalability!
COSMO General Meeting 2010

19. Scalability of COSMO-EU: 665  657  40, 24h
COSMO General Meeting 2010

20. Scalability of COSMO-DE: 421  461  50, 21h
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21. Scalability of COSMO-Europe: 1500 1500  50, 2.8 km, 3 h, no output
COSMO General Meeting 2010

22. The Problems of the COSMO-Code …
I/O: Accessing the disks and the global communication involved disturbes scalability heavily.
Although the communications besides I/O are almost all local, the speedup degrades when using many processors.
What cannot be seen on the pictures before: Although the speedup of the computations is not bad, the efficiency of the code is not satisfying:
NEC SX-9: 13 % of peak
IBM pwr6: about 5-6 % of peak
Cray XT4: about 3-4 % of peak (?)
COSMO General Meeting 2010

23. More Background Swiss national initiative HP2C
High Performance High Productivity Computing
Plan: Enable software to run efficiently on new computer architectures (multi-core, many-core, GP-GPUs, etc.)
ETH Zürich is taking part with the COSMO-CLM: HP2C-CCLM
This project has 3 subtasks
Cloud-resolving climate-change scenarios
Preparing the CCLM and existing model extensions for future computers
Refactoring CCLM components for emerging architectures
HP2C-CCLM runs from Spring 2010 to December 2012
COSMO General Meeting 2010

24. Finally: PP POMPA
POMPA is the „missing link“ between the Swiss national initiative and our consortium
POMPA gives additional resources in the optimization of the COSMO-Model for future computer architectures
POMPA can ensure that the operational COSMO-Model really benefits from the outcomes of HP2C-CCLM
COSMO General Meeting 2010

25. Thank you very much for your attention 06.09.2010
COSMO General Meeting 2010