The length of an uncoupled model run is controlled by the variable npt.
It is the total number of time steps taken in an integration. The value
of npt is not used in a coupled run, since the point at which integration
is stopped is determined by the coupler. The length of a coupled run should be
set in the
CCSM scripts (http://www.cesm.ucar.edu/models/ccsm3.0/ccsm).