My summer job as a research student of Steve Easterbrook is nearing an end. All of a sudden, I only have a few days left, and the weather is (thankfully) cooling down as autumn approaches. It feels like just a few weeks ago that this summer was beginning!

Over the past three months, I examined seven different GCMs from Canada, the United States, and Europe. Based on the source code, documentation, and correspondence with scientists, I uncovered the underlying architecture of each model. This was represented in a set of diagrams. You can view full-sized versions here:

• Diagram key
• COSMOS 1.2.1
• Model E (17/06/2011)
• HadGEM3 (03/08/2009) We are working on getting access to more recent source code for this model, as it is using a new land component now.
• CESM 1.0.3
• GFDL CM 2.1
• IPSLCM5A
• UVic ESCM 2.9

The component bubbles are to scale (based on the size of the code base) within each model, but not between models. The size and complexity of each GCM varies greatly, as can be seen below. UVic is by far the least complex model – it is arguably closer to an EMIC than a full GCM.

I came across many insights while comparing GCM architectures, regarding how modular components are, how extensively the coupler is used, and how complexity is distributed between components. I wrote some of these observations up into the poster I presented last week to the computer science department. My references can be seen here.

A big thanks to the scientists who answered questions about their work developing GCMs: Gavin Schmidt (Model E); Michael Eby (UVic); Tim Johns (HadGEM3); Arnaud Caubel, Marie-Alice Foujols, and Anne Cozic (IPSL); and Gary Strand (CESM). Additionally, Michael Eby from the University of Victoria was instrumental in improving the diagram design.

Although the summer is nearly over, our research certainly isn’t. I have started writing a more in-depth paper that Steve and I plan to develop during the year. We are also hoping to present our work at the upcoming AGU Fall Meeting, if our abstract gets accepted. Beyond this project, we are also looking at a potential experiment to run on CESM.

I guess I am sort of a scientist now. The line between “student” and “scientist” is blurry. I am taking classes, but also writing papers. Where does one end and the other begin? Regardless of where I am on the spectrum, I think I’m moving in the right direction. If this is what Doing Science means – investigating whatever little path interests me – I’m certainly enjoying it.