Community Modeling in the Atmospheric Sciences

1. Community Modelingin theAtmospheric Sciences Stan Solomon High Altitude Observatory National Center for Atmospheric Research SHINE Meeting • Whistler, BC • 30 July 2007

2. 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.

3. 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.

4. 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

5. 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

6. 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)

7. 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

8. 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

9. 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)

10. 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

11. 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.