A Unified Approach to Coupled AtmosphereOcean Modeling

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A Unified Approach to Coupled Atmosphere-Ocean
Modeling
Alistair Adcroft
John Marshall Chris Hill
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Strategy
Single framework for both Atmosphere and Ocean

• Science / Algorithms
• Universal Dynamical Kernel
• Plug-in Physics
• Computation
• Common software environment
• Performance across many platforms

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Universal Dynamical Kernel

• Same Algorithm
• Grid-point
• Isomorphism
• p, z, s,
• Generalized vertical coordinate
• Leveraging development
• e.g. Automatic Adjoint, Non-hydrostatic,
  Parallelization, ...
• Sociology

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MIT Ocean Model
Non-Hydrostatic Topography
Automatic Adjoint State Estimation
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Atmospheric Cousin

• Proof of Concept
• Isomorphed Ocean Model
• Plug-in Physics (Molteni CINECA)
• Intermediate complexity
• Cloud physics, Radiation, PBL,...
• 2.8 degrees, 5 Levels

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(No Transcript)
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Total Precipitation
NCEP Climatology
Intermediate Model
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Proof of Concept

• Common Dynamical Kernel
• for both Atmosphere and Ocean
• Plug-in Physics

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Computation

• Performance on wide range of platforms
• On node performance
• Scalability on multiple processors
• Portability
• Numerical code looks like typical serial code
• Intuitive to scientific user

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The Wrapper
Wrapper interfaces code to platform
T3E
SX-5
Intel Cluster
O2000
SP-2
User sees the numerical model
SMP Cluster
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Tiling
Wrapper
Numerical Model
Numerical code works within a tile
Wrapper updates overlaps between tiles - EXCHANGE

• Wrapper supports MPI, PVM, Threads, Shared
  Memory,
• Wrapper supplies tunable primitives

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Flexibility

• Optimize layout
• vector, long thin tiles
• cache, many small tiles
• holes!

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Saving time and space
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Performance
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Supercomputing _at_ home
_at_home
100k
_at_away
50M
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Plans at MIT

• Extended Coupled Runs
• Predictability Studies
• Paleo-climate
• Push the resolution in Ocean

Ocean
Atmosphere
10 km
1 km
800 km
30 km
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Packages

• Model has many components
• Advection, Physics, Biology,
• I/O
• communication
• Construct model source by assembly
• Building blocks are packages
• Independent development streams

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Summary
Single framework for both Atmosphere and Ocean

• Universal Dynamical Kernel
• Plug-in packages
• Portable performance

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Z-P Isomorphism