C $Header: /home/ubuntu/mnt/e9_copy/MITgcm/model/inc/SURFACE.h,v 1.4.4.2 2003/03/07 05:31:47 heimbach Exp $
C $Name:  $
C
CBOP
C    !ROUTINE: SURFACE.h
C    !INTERFACE:
C    include SURFACE.h
C    !DESCRIPTION: \bv
C     *==========================================================*
C     | SURFACE.h                                                 
C     | o Header file defining surface-related model varaibles    
C     *==========================================================*
C     | Contains variables relative to the surface position       
C     | that are held fixed in linear free-surface formulation    
C     | but can vary with time with a non-linear free-surface.    
C     *==========================================================*
C     \ev
CEOP

C--   COMMON /SURF_FIXED/  fixed surface arrays (Real)
C     Bo_surf  :: Boyancy|1/rho [ocean|atmos] at surface level [=g|alpha(p_o)]
C     recip_Bo :: 1/Bo_surf
C     topoZ    :: topographic height [m] (used mainly for atmosphere)
C     phi0surf :: starting point for integrating phi'_Hyd
      COMMON /SURF_FIXED/ Bo_surf, recip_Bo, topoZ, phi0surf
      _RL  Bo_surf (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
      _RL  recip_Bo(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
      _RS  topoZ   (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
      _RS  phi0surf(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)

C--   COMMON /SURF_INDEX/ Common block for surface related index
C     ksurfC ::  vertical index of the surface tracer cell
C     ksurfW ::  vertical index of the surface U point 
C     ksurfS ::  vertical index of the surface V point 
C IMPORTANT:  ksurfC,W,S = Nr+1  where the fluid column is empty (continent)
      COMMON /SURF_INDEX/ ksurfC, ksurfW, ksurfS
      INTEGER ksurfC(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
      INTEGER ksurfW(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
      INTEGER ksurfS(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)

#ifdef EXACT_CONSERV
C     hDivFlow :: Div. Barotropic Flow at current time [transport unit m3/s]
      COMMON /EXACT_ETA_LOCAL/ hDivFlow
      _RL hDivFlow(1-Olx:sNx+Olx,1-Oly:sNy+Oly,nSx,nSy)
#endif

#ifdef NONLIN_FRSURF
C--   COMMON /SURF_CHANGE/ transient variables used for Non-Lin Free-Surf
C     hFac_surfC ::  New thickness factor of the surface level
C                        center (Tracer point)
C     hFac_surfW ::  idem, West  interface (U point)
C     hFac_surfS ::  idem, South interface (V point)
C     PmEpR :: keep the fresh water input (=-EmPmR) of the previous time step
      COMMON /SURF_CHANGE/
     &     hFac_surfC, hFac_surfW, hFac_surfS, 
     &     PmEpR
      _RS  hFac_surfC(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
      _RS  hFac_surfW(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
      _RS  hFac_surfS(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
      _RS  PmEpR(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)

C--   COMMON /RSTAR_CHANGE/ transient variables used with r* Coordinate
C     rStarFacC :: = dr/dr* = ratio of r-thickness / r*-thickness = h^n / H
C     rStarFacW :: same but for West  face
C     rStarFacS :: same but for South face
C     rStarExpC :: column expansion factor = h^n+1/h^n , Centered
C     rStarExpW :: column expansion factor = h^n+1/h^n , Western  face
C     rStarExpS :: column expansion factor = h^n+1/h^n , Southern face
C     rStarDhCDt:: relative time derivative of h_Center = d.eta/dt / H 
C     rStarDhWDt:: relative time derivative of h_West_face  (u.point)
C     rStarDhSDt:: relative time derivative of h_South_face (v.point)
      COMMON /RSTAR_CHANGE/
     &     rStarFacC, rStarFacW, rStarFacS,
     &     rStarExpC, rStarExpW, rStarExpS,
     &     rStarDhCDt,rStarDhWDt,rStarDhSDt
      _RL  rStarFacC (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
      _RL  rStarFacW (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
      _RL  rStarFacS (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
      _RL  rStarExpC (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
      _RL  rStarExpW (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
      _RL  rStarExpS (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
      _RL  rStarDhCDt(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
      _RL  rStarDhWDt(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
      _RL  rStarDhSDt(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)

C--   COMMON /RSTAR_FIXED/ fixed thickness ratio ( r* discretization )
C     h0FacC :: initial (and fixed in time) hFacC factor
C     h0FacW :: initial (and fixed in time) hFacW factor
C     h0FacS :: initial (and fixed in time) hFacS factor
      COMMON /RSTAR_FIXED/
     & h0FacC, h0FacW, h0FacS
      _RS h0FacC(1-OLx:sNx+OLx,1-OLy:sNy+OLy,Nr,nSx,nSy)
      _RS h0FacW(1-OLx:sNx+OLx,1-OLy:sNy+OLy,Nr,nSx,nSy)
      _RS h0FacS(1-OLx:sNx+OLx,1-OLy:sNy+OLy,Nr,nSx,nSy)

#endif /* NONLIN_FRSURF */