C $Header: /home/ubuntu/mnt/e9_copy/MITgcm/pkg/generic_advdiff/GAD_OPTIONS.h,v 1.10 2008/04/18 19:39:48 jahn Exp $
C $Name:  $

CBOP
C !ROUTINE: GAD_OPTIONS.h

C !INTERFACE:
C #include "GAD_OPTIONS.h" 

C !DESCRIPTION:
C Contains CPP macros/flags for controlling optional features of package.
CEOP

C CPP options file for GAD (Generic Advection Diffusion) package
C
C Use this file for selecting options within the GAD package

#ifndef GAD_OPTIONS_H
#define GAD_OPTIONS_H
#include "PACKAGES_CONFIG.h"
#ifdef ALLOW_GENERIC_ADVDIFF

#include "CPP_OPTIONS.h"

C This flag selects the form of COSINE(lat) scaling of bi-harmonic term.
C *only for use on a lat-lon grid*
C Setting this flag here only affects the bi-harmonic tracer terms; to
C use COSINEMETH_III in the momentum equations set it CPP_OPTIONS.h
#define COSINEMETH_III

C This selects isotropic scaling of harmonic and bi-harmonic term when
C using the COSINE(lat) scaling.
C Setting this flag here only affects the tracer diffusion terms; to
C use ISOTROPIC_COS_SCALING of the horizontal viscosity terms in the 
C momentum equations set it CPP_OPTIONS.h; the following line
C even overrides setting the flag in CPP_OPTIONS.h
#undef ISOTROPIC_COS_SCALING

C As of checkpoint41, the inclusion of multi-dimensional advection
C introduces excessive recomputation/storage for the adjoint.
C We can disable it here using CPP because run-time flags are insufficient.
#undef DISABLE_MULTIDIM_ADVECTION

C This enable the use of 2nd-Order Moment advection scheme (Prather, 1986)
C due to large memory space (10 times more / tracer) requirement,
C by default, this part of the code is not compiled.
#undef GAD_ALLOW_SOM_ADVECT

C Hack to make Redi positive by restricting the outgoing flux for each cell
C to be no more than the amount of tracer in the cell (see Smolarkiewicz 
C MWR 1989 and Bott MWR 1989).  This affects all contributions to the
C tracer equation calculated in gad_calc_rhs, i.e., diffusion, GMRedi and
C the non-local part of KPP, but advection only if 
C multiDimAdvection=.FALSE. and vertical diffusion (including the
C diagonal contribution from GMRedi) only if implicitDiffusion=.FALSE.
C GM is affected only if GMREDI_AdvForm=.FALSE.
C The parameter SmolarkiewiczMaxFrac (set in gad_init_fixed) can be used to
C restrict the fraction of tracer that can leave a cell to be less than 1.
C This will be necessary to make the tracer strictly positive.
C This hack applies to all tracers except temperature! 
#undef  GAD_SMOLARKIEWICZ_HACK

#else

C If GAD is disabled then so is multi-dimensional advection
#define DISABLE_MULTIDIM_ADVECTION

#endif /* ALLOW_GENERIC_ADVDIFF */
#endif /* GAD_OPTIONS_H */