Currently, advection of momentum is always done by leapfrog centered advection with periodic 'mixing' steps. For tracer advection, three options are available. The first is standard leapfrog centered advection; the second is a 3rd-order upwinding [Leonard] which, although not monotone, will improve monotonicity at a somewhat increased computational cost, and the third, available only in CESM1 POP2, is a one-dimensional Lax-Wendroff with one-dimensional flux limiters.

Table: Advection namelist
&advect_nml LANL
default		 CESM1
dipole-grid default		 CESM1
tripole-grid default		 Valid
values		 Advection methods for tracers
tadvect_ctype'centered''upwind3''centered''centered', 'upwind3', 'lw_lim'centered differences, 3rd-order upwinding or 1-D Lax-Wendroff with 1-D flux limiters
/