C $Header: /home/ubuntu/mnt/e9_copy/MITgcm/pkg/generic_advdiff/GAD.h,v 1.6 2001/09/04 14:53:11 adcroft Exp $
C $Name:  $

C Enumerated constants for selecting advection schemes
C  - unfortunately, there is no easy way to make use of the
C    tokens in namelist input so for now we have to enter the
C    tokens value into "data" (ie. 2 for 2nd order etc.)

C Centered 2nd order
      INTEGER ENUM_CENTERED_2ND
      PARAMETER(ENUM_CENTERED_2ND=2)

C 3rd order upwind 
      INTEGER ENUM_UPWIND_3RD
      PARAMETER(ENUM_UPWIND_3RD=3)

C Centered 4th order
      INTEGER ENUM_CENTERED_4TH
      PARAMETER(ENUM_CENTERED_4TH=4)

C Non-linear flux limiter
      INTEGER ENUM_FLUX_LIMIT
      PARAMETER(ENUM_FLUX_LIMIT=77)

C 3-DST 
      INTEGER ENUM_DST3
      PARAMETER(ENUM_DST3=30)

C 3-DST flux limited
      INTEGER ENUM_DST3_FLUX_LIMIT
      PARAMETER(ENUM_DST3_FLUX_LIMIT=33)

C Third/fourth order interpolation factor
      _RL oneSixth
      PARAMETER(oneSixth=1.D0/6.D0)

C Differentiate between tracers (only needed for KPP -  arrgh!!!)
      INTEGER GAD_TEMPERATURE
      PARAMETER(GAD_TEMPERATURE=101)
      INTEGER GAD_SALINITY
      PARAMETER(GAD_SALINITY=102)
      INTEGER GAD_TR1
      PARAMETER(GAD_TR1=103)