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Successful VVUQ Workshop

posted 30 Apr 2019, 07:10 by Daniel Thiemert   [ updated 30 Apr 2019, 07:11 ]

The VVUQ workshop (part of the WP4 of the project) took place on April, the 23rd and 24th in Saint-Rémy-les-Chevreuse, near CEA Saclay.
Extensive descriptions of the VVUQ methodologies as performed on both the URANIE and NWP communities were presented, allowing the various members of the project to become more familiar with both approaches.

Thanks to the presentation of W. Edeling, the link was also made with the VECMA H2020 project where UQ analysis plays a critical role.

The workshop hence allowed to precise:
  1. The common notions that everyone should (physical parameters vs initial conditions, verification vs validation, etc...). Those concepts will form the backbone of the deliverable to come.
  2. The work that will be performed in the rest of the project, notably the fact that the focus will mainly be on the UQ analysis of physical parameters.
  3. In-depth the functionalities of the URANIE tool, as well as first results on how to apply it for NWP analysis.
Finally, in parallel of the workshop BSC and CEA discussed about technical aspects of the current status of the URANIE code and how to improve the workflow internals and specific I/O management issues.

The main outcome of the workshop will be deliverable D4.1 published in June.

Presentations are available on the workshop page.

Definition of a Domain Specific Language for weather and climate prediction

posted 12 Apr 2019, 04:29 by Daniel Thiemert   [ updated 12 Apr 2019, 04:31 ]

DSL Tool Chain
One of the aims of WP2 of ESCAPE-2 is to define, develop and apply a domain-specific language (DSL) toolchain applicable to a comprehensive list of algorithmic motifs (dwarfs) in weather and climate prediction. Domain specific languages are powerful tools that provide programming environments that allow to write numerical scientific algorithms in a concise and high-level language.

The weather and climate domain is characterized by very specific algorithmic motifs derived from the discretization of the numerical methods employed in the mathematical models, the specific aspect ratio of horizontal to vertical grids in regional and global models, and the use of sub-gridscale parametrization characterized by different algorithmic patterns.

This motivates the development of a description suitable for these specific domain characteristics, using a highly concise and readable language. Details such as explicit loops, ordering of the loop nest, data layout or optimizations such as tiling are hardware specific optimizations that are abstracted away from such a high-level language.

Among other things, the DSL language is abstracting away all the details of an efficient parallel implementation and the hardware dependent programming models and optimizations. There are several examples of DSLs being developed and applied to production weather and climate models, like COSMO GridTools (Gysiet al, 2015), the PSyclone for the LFRic model (Adams et al) or the CLAW DSL for column based parameterizations (Clement et al).

In contrast to the existing approaches, that are normally specifically developed for a particular model, the ESCAPE-2 DSL aims at developing a modular toolchain, that supports a wide range of models, numerical methods and grids, by adopting a modular design where domain specific frontends or optimizers can be easily incorporated into the toolchain. Additionally, most of the existing approaches provide a prescriptive language, where the user still has to provide information crucial for parallelization of the algorithm and to obtain good performance. Instead the goal of this document is to provide a high-level descriptive language where the algorithms are described in a sequential manner. The parallelization and optimization implementations are derived by the set of optimizers incorporated in the toolchain.

The recently finalized deliverable D2.1 "High-level domain-specific language (DSL) specification" presents a first definition of a high-level DSL language that is capable of supporting most of the computational patterns present in the models that participate in the ESCAPE-2 project. The document is the outcome of an iterative process and discussions between DSL experts and key model developers. It delivers an extensive and comprehensive grammar, from a holistic perspective where the aim is to provide a unified standard language and HIR (High-level intermediate representation) definition that can deal with a broad spectrum of methods and models. The proposal is a change of paradigm and current state of the art of abstractions and DSLs, where the established tools support only a restricted set of methods or models.

The grammar defined in this document will be the basis of a DSL frontend (D2.2, September 2019) and toolchain implementation (D2.5 May 2021) that will be demonstrated in a set of dwarfs with representative computations from the different models that participate in the project (D2.4 September 2020).

Workshop on VVUQ

posted 14 Feb 2019, 08:01 by Daniel Thiemert   [ updated 14 Feb 2019, 08:02 ]

The ESCAPE-2 project will organise a workshop on VVUQ from 23rd to 24th of April in France. This workshop will serve as a basis for the definition of a common VVUQ (Verification Validation and Uncertainty Quantification) framework as to be applied in Numerical Weather Prediction. Both URANIE and NWP communities need to agree on a common language and framework to be able to apply VVUQ analysis on the various dwarfs and codes at hand in the ESCAPE-2 project. It is part of the deliverables of WP4.

This workshop will also serve as an exchange basis for the coming tasks of WP4 concerning the handling of high dimensionality. The first discussions on how this should be handled and what are the potential approaches will take place. More here.

Successful Workshop Fault tolerant algorithms and resiliency approaches

posted 28 Jan 2019, 04:10 by Daniel Thiemert   [ updated 28 Jan 2019, 04:11 ]

ESCAPE-2 organised a workshop oh fault tolerant algorithms and resiliency approaches on the 23rd and 24th of January 2019 in Milan, Italy. The workshop consisted of a first day of seminars by experts in systems resilience and fault-tolerant numerical algorithms and a second day of scientific discussions of the same experts with project participants. The presentations gave a detailed picture of the state of the art in the field and established connections with operational workflows and numerical algorithms used in atmospheric applications. 

During the discussion sessions, participants explored more in detail how to complement existing numerical weather and climate prediction models with resilience and fault-tolerance techniques. Specific recommendations included benchmarking NWP data volume and operational requirements, pairing fault-tolerant algorithms with system resilience in consistent workflows, coordinating with vendors to provide detailed hardware fault information, and embedding fault-tolerance in domain-specific language programming paradigms. 

The conclusions of the workshop will feature in a white paper to be submitted as an ESCAPE-2 project deliverable, and will inform the investigation of hardware and software resiliency tools within existing and future ESCAPE-2 project dwarfs. Presentations can be found on the workshop page.

Kick-Off Meeting

posted 7 Jan 2019, 00:26 by Daniel Thiemert   [ updated 7 Jan 2019, 00:27 ]

The ESCAPE-2 project on energy-efficient scalable algorithms for weather and climate prediction at the exascale was formally launched with a kick-off meeting at ECMWF from 2 to 4 October 2018.
It will build on the success of the ESCAPE project, which has achieved remarkable gains in computing efficiency by developing the concept of ‘weather and climate dwarfs’.
Like its predecessor, ESCAPE-2 is a three-year project coordinated by ECMWF and funded by the European Commission’s Horizon 2020 Future and Emerging Technologies for High-Performance Computing (FET-HPC) programme.
It brings together 12 partners, including national meteorological and hydrological services, HPC centres, hardware vendors and universities.

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