The road to regional coupled modelling (rCM3)

Earth System Coupled Model
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Hi All.

One of 21stCenturyWeather’s aims is to be build a regional coupled model, combining high resolution atmospheric and ocean models.

I posted this thread on the 21stCenturyWeather Cumulus website, but I thought I’d cross-post it here to get some extra attention (it was a little love-starved over there).

"Following on from Monday’s Modelling Science. meeting, I thought I’d take a high-level look at rAM3 and CM3 and see how they work.

Here is a high-level simplified view of rAM3 from a rose/cylc view.

CM3-tasks-2
CM3-tasks-21738×2968 423 KB

Note rAM3 uses a pre-built executable.

The running of CM3 is in contrast, rather opaque from a rose/cylc viewpoint. It only has four major tasks.

CM3-tasks-3
CM3-tasks-3899×1792 55.2 KB

It’s easy to understand the Recon and Atmos tasks from a UM point of view, but I’m unsure how the coupling is done. This suggests the Atmosphere task is configured via the UM namelists and other MOM6/CICE/NUOPCY control files and the UM executable directly handles the execution of MOM6, CICE and NUOPCY coupling.

Is this correct?

Or does the compiled NUOPCY executable control the UM, MOM6, and CICE?

BTW I can’t find any reference to CABLE in the cm3-suite, but I see plenty of JULES. Does the NUOPCY version of CM3 use JULES?"

(Updated to include the correct rAM3 diagram- thanks @bethanwhite )

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Hi @Paul.Gregory, exciting to hear about the plans for the regional coupling! Just jumping in with a few details re CM3. @kieranricardo will be able to clarify in a bit more detail when he is back!

As CM3 is still in development there is a bit of clean up that could still be done to make the suite a bit clearer.

Or does the compiled NUOPCY executable control the UM, MOM6, and CICE?

This is correct, in the NUOPC setup, a single executable is built from a NUOPC driver which loads in each of the component models as libraries. This driver then controls all the components and the mediator during the run.

BTW I can’t find any reference to CABLE in the cm3-suite, but I see plenty of JULES. Does the NUOPCY version of CM3 use JULES?"

CM3 is currently still using Jules, but the plan is to swap to CABLE.

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