# Summer School on Global Sustainability-Projects & Working Groups

### From Santa Fe Institute Events Wiki

 Summer School on Global Sustainability

## GROUP ASSIGNMENTS

### ENGLAND & NAKICENOVIC: Bush, Cullenward, Frisch, Nguyen, Nkem, Robinson

07/15/09 - Climate models An overview was first given about the definition, classification, characteristics and advantages of a climate model. The process of building a model extends to verification, validation and assessment. What is a climate model? A representation of reality predictive or diagnostic (zooms into reality in the past). Iconic = physcial version, analogue = reproduce behavior and mathematical = analytical relationships that govern events Computer models are advantageous in terms of expense, comprehensiveness, logic, accessiblity, flexibility (capable of examining, sensitivity analysis, parameter tuning etc). There are 6 governing equations in climate models: for ocean there are 3 of momentum, conservation for heat, salt, and mass and the same is for the atmosphere with humidity instead of salt. They have as many equations as unknowns. Forcing conditions represent only processes at the top of the atmosphere for full blown climate models. For running submodels or subcomponents of the Earth it requires many more forcing conditions that need to be addressed. Hence it is harder to run submodels rather than a whole model.

It would be interesting to track down the progress, quantitatively and qualitatively, of the scientific modeling community.

For the most part models are run on FORTRAN90. The language is better in picking out errors in floating points.

What kind of grid is employed determines what kind of dynamics it will represent effectively. About resolution, in the late 80s, the resolution is (4 degrees by 4 degrees) 400km by 400km. Now it is about 1 degree by 1 degree. When we can't get what we want, we go down to a finer resolution by nesting a subgrid of fine scale on top of a coarse grid. Sometimes we have to change the model or some models give us the option of where to zoom in. The option of nesting different resolutions allows for adding in the affects of cities, etc that are quite small but can effect local weather/climate significantly. The vertical vs. horizontal resolution is another issues. A spectral grid is such that the lines are parallel along the y axis but bend along the x axis. 1D e.g. that about an air column in the atmosphere and 2D models e.g. Henry Stommel's 2-boxes models still have good uses on their own. 3D models employ spectral grids which minimize numerical erros in atmospheric models.

How much time it would normally take for a model to be ready for use? The process of running a model to get its output and spatial visualization are seperate. Having models is one thing, having interfaces where researchers will simply walk in and use it is another option and there are some good ones. Archives of observations are very important to test our models. But sometimes the archives are in very complicated formats even to view e.g. the Jet Propulsion Lab prefers .hdf - why do they make it so inaccessible?

There are good models and fake ones that look like real. This is not a parade. Open access is important.

CFC invade the ocean in very specific way and they act as tracers in ocean circulation experiment. As these were introduced, the presence/levels of CFCs in deep water provides an excellent sense of movement and mixing. This can be used to doublecheck the accuracy of ocean models, being more precise than temperature and salinity checks... To assess uncertainties in existing models, lland ice is a big uncertainty (1.6m is likely sealevel rise, 85cm from land ice) Another is sulfite areosols–a pollutant that has helped to keep things cooler. as we clean up our combustion, this will change–the impacts of this are uncertain

### RUSSELL & GRÜBLER: Bamutaze, Borgeson, Engler, Ona, Pasqualini, Zellner

Media:Russel_summary.doc Here is the summary of Joellen Russel's climate modeling talks.

## Participation

Active, assertive participation by students is an intrinsic part of this event. Attendance at all program sessions is mandatory. Participants have been divided into six groups; each group designed to be as topically and geographically diverse as possible. Chairperson and rapporteur roles may rotate within each group.