Physics
CCAM supports various parameterisations for atmospheric physics to represent unresolved atmospheric processes. These parameterisations include:
- Gravity wave drag
- Convection
- Cloud microphysics
- Radiation
- Turbulent mixing
The CCAM gravity wave drag parameterisation is currently based on chouinard1986_gwdrag.pdf
The CCAM convection parameterisation is currently based on mcgregor2003_convection.pdf
CCAM supports a (single moment) prognostic cloud condensate scheme from Mk3.6, but with modifications for dynamical downscaling. There are various modes of the cloud microphysics that are described at the following link ncloud. In summary, CCAM supports:
- Prognostic water vapour, liquid cloud water and frozen cloud water
- Prognostic water vapour, liquid and frozen cloud water, as well as prognostic rain, snow and graupel
A double moment parameterisation is also available.
The CCAM cloud microphysics paramaterisation is currently based on the following publications rotstayn1997_microphys1.pdf and lin1983_microphys3.pdf
The CCAM radiation parameterisations is based on the GFDL-CM3 radiation code, with modifications for CMIP6 radiative forcings. A description of the model can be found at the following links freidenreich1999_swradiation5.pdf and schwarzkopf1999_lwradiation5.pdf
CCAM currently has different options for turbulent mixing in the atmosphere and in the ocean. Both the atmosphere and ocean mixing can also be combined into a single implicit parameterisation, which better conserves momentum fluxes and a more robust design for heat exchange. For atmospheric mixing, CCAM supports a local-Ri parameterisation and a k-e turbulence closure parameterisation described by hurley2007_vertmixing6.pdf . The CCAM ocean mixing supports both a K-profile approach ( large1993_mixedlayerocean1.pdf ) and a k-e closure based on the SHOC model. If k-e approaches are selected for both the atmosphere and ocean, then both schemes are integrated into a combined parameterisation.