CCSM coupled model is based on a framework which divides the complete climate
system into component models connected by a coupler. This design requires four
component models -- atmosphere, sea-ice, land, and ocean -- each connected to
the Coupler, and each exchanging data with the Coupler only.
The Climatological Data Atmosphere Model (datm) functions as the atmosphere
component in a CCSM ... configuration. The datm atmosphere component interacts with
the Coupler just like any atmosphere model would, but it is not an active
model, rather, it takes atmosphere data from an input data file and sends it to
the Coupler, ignoring any forcing data received from the Coupler. Typically the
input data file contains mean daily data generated by an active CCSM atmosphere
model (it's unlikely that real world observations exists for all the required
fields). Such a "dummy" atmosphere model is useful for doing ocean + ice spinup
The CCSM Climatological Data Atmosphere Model, version 6.0 (datm6), was
released in June 2004, as part of the CCSM3.0 release.