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JRA1/WP7 - Earth System Models, Tools and Environments: Development and Integration

Objectives

The work package focuses on two key parts of the infrastructure of an earth system model, the coupler and the input-output (I/O) systems. The work is closely associated with JRA2 which looks at the performance of the models themselves. The user survey to be carried out in Task 1 seeks to ensure the requirements of climate scientists are fully accounted for in both JRA1 and JRA2.

 

Three issues complicate the development of ESMs, and require a community response to the problem. The increasing parallelisation of supercomputers means that the coupler and I/O systems require significant development to prevent them becoming bottlenecks to model performance. The scientific need to couple more models and have more choice of diagnostic output means that the coupler and I/O infrastructure have to be more flexible. Shared use of community models and model subsystems means that they have to be portable, and they have to perform well on a variety of computer platforms.

 

The OASIS coupler is a software tool currently used by approximately 25 climate modelling groups internationally for exchanging coupling information between numerical codes representing different components of the climate system. As the climate modelling community is progressively targeting higher resolution climate simulations run on massively parallel platforms, a new fully parallel version of the coupler, OASIS4, is currently being developed; in addition to the 2D fields supported by OASIS3, OASIS4 supports 3D coupling. OASIS4 is currently in a beta testing phase. Task 2 will complete development of the fully parallel coupler, test it in partnership with the main users and undertake further developments prioritised according to the user survey.

 

A number of different strategies are appropriate for optimising the I/O infrastructure on parallel computers which depend on the platform, the application and the model configuration. Task 3 will undertake the developments of parallel I/O systems and I/O servers focussed on a range of platforms and applications. The benefits of each will be compared and generic solutions targeted at all models will be developed.

 

The results of the user survey will provide the focus for bringing together the infrastructure developments in this WP and in JRA2. The user survey will also deliver a comprehensive overview of climate science requirements within Europe.

See the full description in the DoW

 

Progress

 

Work done in the work package includes ongoing development of the OASIS4 coupler to meet the infrastructure needs of high resolution climate models, and prototyping of parallelised IO with a view to sharing experiences. A user survey was conducted to inform the work of WP7 and WP8.

 

Details for each task:

 

Task 0: WP Coordination:

On-going technical coordination of the WP and management interaction for the project.

Task 1: User Survey

A questionnaire on models, coupling and performance was prepared by the Met Office and the University of Manchester (UNIMAN) and distributed around Europe. Seventeen replies were received from 12 different countries. The results of the survey (M7.1) were passed onto members of work package 7 and 8 to refine the requirements of planned work. Difficulty in obtaining a sufficient number of responses to the questionnaire meant that analysis of the questionnaire was delivered later than planned.

 

Task 2: OASIS4 Development

1) Validation, testing and bug-fixing of the global search for the 2D conservative remapping
2)Implementation of global conservation

3) Implementation of the possibility to use user-defined sets of weights-and-addresses for the interpolation
4) Development of a Graphical User Interface for the realization of the XML configuration files
5) Simplification of the XML configuration files and optimisation of the XML reading
6) New directory structure for OASIS4 sources

 

Task 3: Parallel IO Improvements

A range of Input/Output (IO) techniques was researched and analysed, and a tutorial presentation created to summarise each one (Deliverable D7.1)

The strategy for progressing the development and deployment of IO technologies was agreed; ongoing technical discussions will continue to refine this. Overall, the intention is to search for solutions and provide generic advice or general purpose applications that will support models and model developers at other European institutions.

 

An IO server technique has been developed and deployed that parallelises the post-processing and writing to files of diagnostic data. This IO system has been implemented in the NEMO model, and is used routinely for CMIP5 climate simulations. The system is ported and assessed on several super-computer (NEC, IBM SP6, BULL Itanium, BULL x86, SGI x86). A new version of the IO system is now under development, using C++ object programming instead of Fortran. It will benefit of several months of experience and feedback from developers and users. 

The strategy for developing and deploying IO technologies (M7.2) is essentially to continue current implementation and testing of IO server and parallel IO developments, to share findings, and to work towards improving. The Met Office will contribute to this strategy by inputting its findings from ongoing developments that are being done separate from the IS-ENES project: to implement a low-level IO server for the Met Office Unified Model targeted to the IBM Power 6 architecture and to develop a diagnostic server.

 

Deliverables


D7.1 A tutorial on parallel IO and IO servers and their benefits

 

 

D7.2 Fully parallelised and optimised version of OASIS4 answering needs of current coupled climate models 
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IS-ENES3 has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 824084