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Community Modelingin the

Atmospheric Sciences

Stan SolomonHigh Altitude Observatory

National Center for Atmospheric Research

SHINE Meeting • Whistler, BC • 30 July 2007

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Why Consider Community Modelsfor Solar/Terrestrial Physics?

Continuing analogy with the weather and climate modeling field

Examples of successful shared code models in solar and astrophysics

(e.g., FLASH, CHIANTI)

Several open-source efforts in applications software and operating systems

(e.g., GNU, Linux)

Increasing agency pressure

E.g., language in NASA Living with a Star Strategic Capabilities AO:

“...all source code must be delivered...for unrestricted use by NASA.”

This is pretty strong; not clear if it will be implemented

In short, there are signs that parts of the research world are headed in this general direction, and disciplines need to consider carefully the options and choices.

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What is a Community Model?

Presupposes that there is a Community

In this context, presume that it is a Community of scientific researchers

Necessary that more than one institution is involved

Implies some degree of support for users

But there is considerable deviation about the mean here

Range spans from “you can have it but you’re on your own” to a full-time staff devoted to helping users

Implies that tools (e.g., source code) will be shared among the Community

In the atmospheric sciences, the concept of a community model often implies that there is participation from the general community in the development, testing, improvement, and goals of the endeavor.

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Software Distribution

There are several software distribution paradigms:

Proprietary

Distribute only executable software or special-purpose hardware

May or may not involve fees

Open Source License

Many types, ranging from very restrictive to completely unrestrictive

May or may not involve fees

Public Domain

Completely unrestrictive

May include disclaimers for protection

There are also several physical distribution methods:

Physical media

On-line, but restricted using registration, accounts, or etc.

On-line, wide open

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How About the Support Problem?

Many people I’ve talked to about Community Models are OK with the general concept but don’t want to spend their life answering dumb questions from novice users.

It’s possible to start small, as a “community model with lower-case c” with the intent to integrate more support as resources permit.

e.g., the Whole Atmosphere Community Climate Model

It only seems possible to fully support a big-deal Community Model in the context of a stable long-term grant, a Government lab, or a FFRDC.

Supercomputing resources also nice to have

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A Few Examples from the Atmospheric Sciences

• Community Climate System Model (CCSM)

• Weather Research Forecast Model (WRF)

• Whole Atmosphere Community Climate Model (WACCM)

• Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM)

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The Community Climate System Model (CCSM)• Large, active community involved in global climate simulations• Central nucleus of full-time scientists, software engineers, support personnel• Working groups, formal recommendations, change procedures, version control• Major annual meeting• Coding standards• Documentation standards• “Matrix” of license agreements

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Weather Research Forecast Mode (WRF)

• High-resolution meteorology model designed and constructed by a medium-sized group at NCAR M3

• Can utilize sophisticated data assimilation techniques

• Openly available to anyone

• Commonly ported to local systems and adapted for specific uses

• Global terrestrial versions, global Mars version, other creative uses

• Limited support for users, but documentation and generalization is good

• Possibly the most successful model ever, with thousands of downloads and hundreds of installations

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Whole Atmosphere Community Climate Model (WACCM)

• A single-code synthesis of CAM3, MOZART, and the TIME-GCM

• Currently extends from the surface to ~150 km altitude; goal is to cover the entire 0 – 500 km range including the thermosphere and ionosphere

• Small group of in-house developers and several more hangers-on

• Moderate-sized community involved in model use or model development

• Coding standards, version control, etc.

• Occasional working groups, meetings, and conferences

• Documentation is coming along

• Code available on the web (generally a version behind)

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Thermosphere-Ionosphere-ElectrodynamicsGeneral Circulation Model (TIE-GCM)

• Developed by Ray Roble, Bob Dickinson, Art Richmond, et al.

• Modest community using model or model results

• Small group of in-house developers and visitors

• Version control, cross-platform release (v. 1.8)

• Code base much improved

• Actually have a user manual now

• No formal distribution arrangement, but anyone who wants the code can have it

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Does This Paradigm Work?

• In the US, the atmospheric sciences are blessed/cursed by a large federally-funded research and development center that can lead and coordinate these activities.

• The university community has mixed feelings about this, because it both provides services and consumes financial resources.

• There is no question that participation, collaboration, and education are facilitated by a Community Modeling approach.

• There is also no question that there are pitfalls, ranging from misuse or misinterpretation of results, to lack of appropriate credit, citation, or acknowledgement.

...but these have close analogies with isses in observational data distribution.