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NEMS and NGGPS integration

Presented By: Hendrik Tolman (NWS/NCEP/EMC)Contributors: EMC senior staff

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NEMS and NGGPS integration

• NEMS is the infrastructure we intend to use to manage a unified coupled modeling suite efficiently.

• In NEMS, we adopt a new dycore, not a full model.– More rapid transition to operations, as many aspects of the

operational models remain the same.• In NEMS, we (intend to) deal with physics in a modular version.• Modular approach allows to

– Do unified modeling, but if necessary, – have various cores and physics packages.– Maintenance of packages is much cheaper than of full models,

and therefore – NEMS in principle allow for cheaper multi-model approaches

too.

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NGGPS and NEMS / ESMF

Modular modeling, using ESMF to modularize elements in fully coupled unified global model

( + ionosphere , ecosystems , …… )Presently available dycores are GSM, NAM, FIM.

Physics interface v1.0 delivered June 2015.

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NGGPS physics

Atmosphere Model including Dynamics

Dt, u, v, w, T, q, p, z, qx, cx, ax

destaggeredTendencies

and Updates

InitMode

Dynamical equations, advection, horizontal mixing, diffusion.

Radiation Deep and Shallow Cumulus

Surface Layer

PBL and Vertical Mixing

Micro-physics

Modified Kalnay Rules Layer

NUOPC Physics Driver Schematic

OutputDiagnostics• fields• rates• budgets• others

Atmospheric Physics Driver(init, run, finalize modes)

InitializePhysics

Tables and Databases

FinalizeMode.

standard interface for model physics

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System Evolution Over the Next 5 Years

Common Physics Interface V1.0 delivered June 2015

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Why System(s) are Operational

Top 3 System Performance Strengths• Modularity allows for coupled modeling and development of component

models both to be (relatively) simple.• Allows for unified modeling approach, but also allows for various

component models to be interchanged in a relatively simple way.• Update / addition of component models in principle does not require

change in infrastructure, making R2O in principle much more efficient.

Top 3 System Performance Challenges • Efficiency / simplicity of system (compare, e.g., WRF and CESM)• Limit to as unified a model as possible.• Modular approach is associate with “weak” coupling, unlike fully

integrated component models. The modular approach may prove inefficient on exoscale computing.

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Top 3 Things We Need From the UMAC

1. Endorsement of modular approach.• ESMF NUOPC NEMS

2. Community involvement of development.• Community modeling approach,• Reassess / develop requirements.• Assessment of strengths and weaknesses.

3. How to involve existing community better• USA: e.g., CESM• Europe ?