The aquaplanet configuration in CESM allows the user to run CAM above an entirely ocean covered surface. The surface model is essentially a data ocean model where SST has to be specified. There are a standard set based on the AquaPlanet Experiment project (Neale & Hoskins, Williamson). The advantage of an aquaplanet configuration is that it allows the user to run the full CAM parameterization suite while retaining much simpler surface conditions than the complex combintation of land, ocean and sea-ice seen in the real world. This configuration is frequently seen as a bridging test of a GCM bewteen more idealized dynamical core experiments with rudimentary represenations of physical processes and and prescribed SST AMIP experiments. The CAM5 aquaplanet configuration is described by Medeiros et al. (2016).
Medeiros, B., D. L. Williamson, and J. G. Olson, 2016: Reference aquaplanet climate in the com- munity atmosphere model, version 5. Journal of Advances in Modeling Earth Systems, doi: 10.1002/2015MS000593
Neale, R. B. and B. J. Hoskins, 2000a: A standard test for AGCMs including their physical parametrizations. I: The proposal. Atmos. Sci. Lett., 1, 101-107.
David L. Williamson and Co-Authors, 2012: The APE Atlas. Technical report, National Center for Atmospheric Research. URL http://nldr.library.ucar.edu/repository/collections/TECH-NOTE-000-000-000-865.
Aqua-planet simulations can be run in CESM using the following compsets:
Be aware that these may not produce a "reference" aquaplanet (Medeiros et al. 2016) due to the default settings and boundary conditions that the model retrieves.
Running the slab-ocean aquaplanet is not currently (CESM1) implemented as a standard compset. An experimental configuration can be achieved with a few steps. Notes on one approach are included in the file available for download here.