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.
|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|