[GTP] Joint GTP MMM seminar--Oliver Fuhrer

[Silvia Gentile]

Preparing the Numerical Weather Prediction Model COSMO Emerging Hardware 
Technologies
Oliver Fuhrer*
MeteoSwiss

Friday July 29
NCAR Mesa Laboratory
1850 Table Mesa Drive
Main Auditorium
Lecture 10:00am


The available computer power is the most important constraint limiting 
the horizontal resolution, the complexity of the model system, and the 
number of ensemble members of numerical weather prediction and regional 
climate models. In order to leverage emerging supercomputers, current 
climate and weather prediction codes will have to be adapted. To this 
end, the HP2C COSMO project carried out in the framework of the Swiss 
HP2C (High Performance High Productivity Computing) initiative aims at 
re-engineering the numerical weather prediction and regional climate 
model COSMO (Consortium of Small-Scale Modeling) with the aim to produce 
a single code which runs efficiently on both massively parallel scalar 
machines as well as heterogeneous systems with GPUs (Graphical Processor 
Units).
In this talk, the approach taken is illustrated by two opposing 
examples. The first example is the non-hydrostatic dynamical core, which 
is being completely rewritten in C++ using modern software engineering 
and a DSEL (domain specific embedded language) like approach. The DSEL 
is based on a stencil library which abstracts the basic algorithmic 
motif of explicit finite differences and allows for efficient 
implementation both on multicore CPUs and GPUs. The second examples are 
the physical parametrizations. Since a complete rewrite of the physical 
parametrizations is neither feasible nor acceptable by the developer 
community, a compiler directive based approach has been selected. 
Nevertheless, results indicate that considerable changes are necessary 
to the physics code in order to fully take advantage of the various 
parallelism levels available on GPU hardware. Performance results of 
both examples above are presented.
Lessons learnt from these efforts and a brief outlook on the next steps 
that will be undertaken in the project are presented.
*In collaboration with Xavier Lapillone (C2SM/ETH), Tobias Gysi (SCS 
AG), Thomas Schulthess (CSCS/ETH)


Friday July 29
NCAR Mesa Laboratory
1850 Table Mesa Drive
Main Auditorium
Lecture 10:00am

-- 
Silvia Gentile
NCAR IMAGe
1850 Table Mesa Drive
Boulder, CO 803035
www2.image.ucar.edu/IMAGe