Geog 657 General Circulation Model

Spring 2018 – Instructions for final GCM experiment.

Your assignment is to produce a five year perturbation (“experiment”) run of CAM3, which you may compare to the control run provided.

  1. 1.Perturbations can be generated from the namelist input, from the boundary condition files, or from modifications of the code. The latter choice is not recommended unless you are positive of what your effects will be.

  2. 2.Set up nelapse to handle a four-month spinup followed by five calendar years that will actually be used.

  3. 3.See the work/cam3cr13s for namelists used in the control run. The h0 history files were basically default monthly averages.  H1 was set to save a small number of energy balance fluxes at 5-day intervals, and h2 saves just the temperature and height fields at daily values. If you don’t need them, you don’t need to generate them, but it doesn’t hurt to save them until you start the analysis. If you need more data for your analysis, just keep in mind that you won’t have the control run to compare to.

  4. 4.I recommend that you leave the namelist controls for restart and branch run initialization alone. Once you have the run completed, please remove restart files, initialization files, and any history tape series you don’t need in order to save space.

  5. 5.Final results will be a paper short on text and long on figure captions, after an introduction. Having it just be a PowerPoint file with significant Notes is acceptable.

  6. 6.If it is conceivable to coordinate the type of model run you do with your zonal energy balance model project, that would be nice, and might save you some time.

  7. 7.You will also want to try to coordinate this project with the CMIP analysis project.

Before working on a long CAM run, you should go through a series of setups, test runs, and basic NCL analyses, and then set up the long run. The first test starts here, following which you will be led through a sequence of tests.

Setting up for a test run

Running a short control-run test

Setting up and running a perturbation using namelist controls.

Modifying input data and running a test with modified boundary conditions

Using NCL to analyze the output of the test runs

Once you have completed the tests you can proceed to setting up a long CAM run

Further instructions on setting up the long CAM run are here.

NCL examples for analyzing the long CAM run are here

Additional information:

A reference to the directory structure on Mahoroba

A reference page to the model Users Guides and other references

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April 5, 2018 9:56 AM