1 Community Modeling in the Atmospheric Sciences Stan Solomon High Altitude Observatory National Center for Atmospheric Research SHINE Meeting Whistler, BC 30 July 2007

2 Why Consider Community Models for 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 M 3 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-Electrodynamics General 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.

12 My Personal Experience with Numerical Models GLOW Model Started out as essentially a public domain model Based in part on code or equations that I got from other people Papers: 17 (+ many others) Citations: ~ three hundred Grants: 12 (incl. co-i’s & indirect) Worst thing that ever happened:...the undergrad class assignment Best thing that ever happened...grad student talk at AGU Monte Carlo Auroral Model Started out as private code that I never intended to share with others Some ideas came from the literature, but the code is 100% mine Papers: 4 (2 first author + 2 co-author) Citations: ~ three dozen Grants: 2 Worst thing that ever happened:...didn’t get second grant renewed Best thing that ever happened...finally gave code away Basic “lesson learned” from the last 20 years: Be specific about your expectations.