model/src/forward_step.F

C $Header: /u/gcmpack/MITgcm/model/src/forward_step.F,v 1.92 2004/05/14 21:08:28 heimbach Exp $
C $Name:  $

#include "PACKAGES_CONFIG.h"
#include "CPP_OPTIONS.h"

cswdptr -- add --
#ifdef ALLOW_GCHEM
# include "GCHEM_OPTIONS.h"
#endif
cswdptr -- end add ---

CBOP
C     !ROUTINE: FORWARD_STEP
C     !INTERFACE:
      SUBROUTINE FORWARD_STEP( iloop, myTime, myIter, myThid )

C     !DESCRIPTION: \bv
C     *==================================================================
C     | SUBROUTINE forward_step
C     | o Run the ocean model and, optionally, evaluate a cost function.
C     *==================================================================
C     |
C     | THE_MAIN_LOOP is the toplevel routine for the Tangent Linear and
C     | Adjoint Model Compiler (TAMC). For this purpose the initialization
C     | of the model was split into two parts. Those parameters that do
C     | not depend on a specific model run are set in INITIALISE_FIXED,   
C     | whereas those that do depend on the specific realization are
C     | initialized in INITIALISE_VARIA.   
C     |
C     *==================================================================
C     \ev

C     !USES:
      IMPLICIT NONE
C     == Global variables ==
#include "SIZE.h"
#include "EEPARAMS.h"
#include "PARAMS.h"
#include "DYNVARS.h"

#ifdef ALLOW_SHAP_FILT
# include "SHAP_FILT.h"
#endif
#ifdef ALLOW_ZONAL_FILT
# include "ZONAL_FILT.h"
#endif
#ifdef COMPONENT_MODULE
# include "CPL_PARAMS.h"
#endif

#ifdef ALLOW_AUTODIFF_TAMC
# include "FFIELDS.h"

# ifdef ALLOW_NONHYDROSTATIC
#  include "CG3D.h"
# endif

# include "tamc.h"
# include "ctrl.h"
# include "ctrl_dummy.h"
# include "cost.h"
# include "EOS.h"
# ifdef ALLOW_EXF
#  include "exf_fields.h"
#  include "exf_clim_fields.h"
#  ifdef ALLOW_BULKFORMULAE
#   include "exf_constants.h"
#  endif
# endif
# ifdef ALLOW_OBCS
#  include "OBCS.h"
# endif
# ifdef ALLOW_PTRACERS
#  include "PTRACERS.h"
# endif
# ifdef ALLOW_CD_CODE
#  include "CD_CODE_VARS.h"
# endif
# ifdef ALLOW_EBM
#  include "EBM.h"
# endif
#endif /* ALLOW_AUTODIFF_TAMC */

C     !LOCAL VARIABLES:
C     == Routine arguments ==
C     note: under the multi-threaded model myiter and 
C           mytime are local variables passed around as routine 
C           arguments. Although this is fiddly it saves the need to 
C           impose additional synchronisation points when they are 
C           updated.
C     myIter - iteration counter for this thread
C     myTime - time counter for this thread
C     myThid - thread number for this instance of the routine.
      INTEGER iloop
      INTEGER myThid 
      INTEGER myIter
      _RL     myTime

C     == Local variables ==
      integer i,L
      INTEGER myItP1
CEOP

#ifdef ALLOW_DEBUG
      IF ( debugLevel .GE. debLevB ) 
     &    CALL DEBUG_ENTER('FORWARD_STEP',myThid)
#endif

#ifdef ALLOW_AUTODIFF_TAMC
C--   Reset the model iteration counter and the model time.
      myiter = nIter0 + (iloop-1)
      mytime = startTime + float(iloop-1)*deltaTclock
#endif

#if (defined (ALLOW_AUTODIFF_TAMC) && defined (ALLOW_AUTODIFF_MONITOR))
C     Include call to a dummy routine. Its adjoint will be 
C     called at the proper place in the adjoint code.
C     The adjoint routine will print out adjoint values 
C     if requested. The location of the call is important, 
C     it has to be after the adjoint of the exchanges 
C     (DO_GTERM_BLOCKING_EXCHANGES).
      CALL DUMMY_IN_STEPPING( myTime, myIter, myThid )
cph   I've commented this line since it may conflict with MITgcm's adjoint
cph   However, need to check whether that's still consistent
cph   with the ecco-branch (it should).
cph      CALL DO_FIELDS_BLOCKING_EXCHANGES( myThid )
#endif

#ifdef EXACT_CONSERV
      IF (exactConserv) THEN
C--   Update etaH(n+1) :
         CALL TIMER_START('UPDATE_ETAH        [FORWARD_STEP]',mythid)
         CALL UPDATE_ETAH( myTime, myIter, myThid )
         CALL TIMER_STOP ('UPDATE_ETAH        [FORWARD_STEP]',mythid)
      ENDIF
#endif /* EXACT_CONSERV */ 

#ifdef NONLIN_FRSURF
      IF ( select_rStar.NE.0 ) THEN
C--   r* : compute the future level thickness according to etaH(n+1) 
          CALL TIMER_START('CALC_R_STAR       [FORWARD_STEP]',mythid)
          CALL CALC_R_STAR(etaH, myTime, myIter, myThid )
          CALL TIMER_STOP ('CALC_R_STAR       [FORWARD_STEP]',mythid)
      ELSEIF ( nonlinFreeSurf.GT.0) THEN
C--   compute the future surface level thickness according to etaH(n+1) 
          CALL TIMER_START('CALC_SURF_DR      [FORWARD_STEP]',mythid)
          CALL CALC_SURF_DR(etaH, myTime, myIter, myThid )
          CALL TIMER_STOP ('CALC_SURF_DR      [FORWARD_STEP]',mythid)
      ENDIF
#endif /* NONLIN_FRSURF */

#ifdef ALLOW_AUTODIFF_TAMC
c**************************************
#include "checkpoint_lev1_directives.h"
c**************************************
#endif

C--   Call external forcing package
#ifdef ALLOW_BULK_FORCE
      IF ( useBulkForce ) THEN
#ifdef ALLOW_DEBUG
       IF ( debugLevel .GE. debLevB ) 
     &    CALL DEBUG_CALL('BULKF_FIELDS_LOAD',myThid)
#endif
       CALL TIMER_START('BULKF_FORCING      [FORWARD_STEP]',mythid)
C-    load all forcing fields at current time
       CALL BULKF_FIELDS_LOAD( myTime, myIter, myThid )
C-    calculate qnet and empmr (and wind stress)
       CALL BULKF_FORCING( myTime, myIter, myThid )
       CALL TIMER_STOP ('BULKF_FORCING      [FORWARD_STEP]',mythid)
      ELSE
#endif /* ALLOW_BULK_FORCE */

# ifdef ALLOW_EXF
#  ifdef ALLOW_DEBUG
      IF ( debugLevel .GE. debLevB ) 
     &    CALL DEBUG_CALL('EXF_GETFORCING',myThid)
#  endif
      CALL TIMER_START('EXF_GETFORCING     [FORWARD_STEP]',mythid)
      CALL EXF_GETFORCING( mytime, myiter, mythid )
      CALL TIMER_STOP ('EXF_GETFORCING     [FORWARD_STEP]',mythid)
# else /* ALLOW_EXF undef */
cph The following IF-statement creates an additional dependency
cph for the forcing fields requiring additional storing.
cph Therefore, the IF-statement will be put between CPP-OPTIONS,
cph assuming that ALLOW_SEAICE has not yet been differentiated.
#  if (defined (ALLOW_SEAICE) || defined (ALLOW_EBM))
      IF ( .NOT. useSEAICE .AND. .NOT. useEBM ) THEN
#  endif
#ifdef ALLOW_DEBUG
       IF ( debugLevel .GE. debLevB ) 
     &    CALL DEBUG_CALL('EXTERNAL_FIELDS_LOAD',myThid)
#endif
       CALL TIMER_START('EXTERNAL_FIELDS_LOAD[FORWARD_STEP]',mythid)
       CALL EXTERNAL_FIELDS_LOAD( mytime, myiter, mythid )
       CALL TIMER_STOP ('EXTERNAL_FIELDS_LOAD[FORWARD_STEP]',mythid)
#  if (defined (ALLOW_SEAICE) || defined (ALLOW_EBM))
      ENDIF
#  endif
# endif /* ALLOW_EXF */
#ifdef ALLOW_BULK_FORCE
C--   end of if/else block useBulfforce --
      ENDIF
#endif /* ALLOW_BULK_FORCE */

#ifdef ALLOW_AUTODIFF
c--   Add control vector for forcing and parameter fields
      if ( myiter .EQ. nIter0 )
     &     CALL CTRL_MAP_FORCING (mythid)
#endif

#ifdef ALLOW_THSICE
      IF ( useThSIce .AND. buoyancyRelation(1:7) .EQ. 'OCEANIC' ) THEN
#ifdef ALLOW_DEBUG
        IF ( debugLevel .GE. debLevB )
     &    CALL DEBUG_CALL('THSICE_MAIN',myThid)
#endif
C--     Step forward Therm.Sea-Ice variables
C       and modify forcing terms including effects from ice
        CALL TIMER_START('THSICE_MAIN        [FORWARD_STEP]', myThid)
        CALL THSICE_MAIN( myTime, myIter, myThid )
        CALL TIMER_STOP( 'THSICE_MAIN        [FORWARD_STEP]', myThid)
      ENDIF
#endif /* ALLOW_THSICE */

# ifdef ALLOW_SEAICE
C--   Call sea ice model to compute forcing/external data fields.  In
C     addition to computing prognostic sea-ice variables and diagnosing the
C     forcing/external data fields that drive the ocean model, SEAICE_MODEL
C     also sets theta to the freezing point under sea-ice.  The implied
C     surface heat flux is then stored in variable surfaceTendencyTice,
C     which is needed by KPP package (kpp_calc.F and kpp_transport_t.F)
C     to diagnose surface buoyancy fluxes and for the non-local transport
C     term.  Because this call precedes model thermodynamics, temperature
C     under sea-ice may not be "exactly" at the freezing point by the time
C     theta is dumped or time-averaged.
      IF ( useSEAICE ) THEN
#ifdef ALLOW_DEBUG
         IF ( debugLevel .GE. debLevB ) 
     &    CALL DEBUG_CALL('SEAICE_MODEL',myThid)
#endif
         CALL TIMER_START('SEAICE_MODEL       [FORWARD_STEP]',myThid)
         CALL SEAICE_MODEL( myTime, myIter, myThid )
         CALL TIMER_STOP ('SEAICE_MODEL       [FORWARD_STEP]',myThid)
      ENDIF
# endif /* ALLOW_SEAICE */

C--   Freeze water at the surface
#ifdef ALLOW_AUTODIFF_TAMC
CADJ STORE theta = comlev1, key = ikey_dynamics
#endif
      IF ( allowFreezing .AND. .NOT. useSEAICE
     &                   .AND. .NOT. useThSIce ) THEN
        CALL FREEZE_SURFACE(  myTime, myIter, myThid )
      ENDIF

#ifdef ALLOW_AUTODIFF_TAMC
# ifdef ALLOW_PTRACERS
cph this replaces _bibj storing of ptracer within thermodynamics
CADJ STORE ptracer  = comlev1, key = ikey_dynamics
# endif
#endif

#ifdef ALLOW_PTRACERS
# ifdef ALLOW_GCHEM
         CALL GCHEM_FIELDS_LOAD( mytime, myiter, mythid )
# endif
#endif

#ifdef COMPONENT_MODULE
       IF ( useCoupler .AND. cpl_earlyExpImpCall ) THEN
C      Post coupling data that I export.
C      Read in coupling data that I import.
         CALL TIMER_START('CPL_EXPORT-IMPORT  [FORWARD_STEP]',myThid)
         CALL CPL_EXPORT_MY_DATA(       myIter, myTime, myThid )
         CALL CPL_IMPORT_EXTERNAL_DATA( myIter, myTime, myThid )
         CALL TIMER_STOP ('CPL_EXPORT-IMPORT  [FORWARD_STEP]',myThid)
       ENDIF
# ifndef ALLOW_AIM
C jmc: don't know precisely where to put this call. leave it here for now.
       IF ( useCoupler ) THEN
         CALL OCN_APPLY_IMPORT( .TRUE., myTime, myIter, myThid )
       ENDIF
# endif
#endif /* COMPONENT_MODULE */

C--     Step forward fields and calculate time tendency terms.

C AMM
#ifdef ALLOW_FIZHI
        if( useFIZHI) then
         CALL TIMER_START('FIZHI               [FORWARD_STEP]',mythid)
         CALL UPDATE_OCEAN_EXPORTS ( myTime, myIter, myThid )
         CALL UPDATE_EARTH_EXPORTS ( myTime, myIter, myThid )
         CALL UPDATE_CHEMISTRY_EXPORTS ( myTime, myIter, myThid )
         CALL FIZHI_WRAPPER ( myTime, myIter, myThid )
         CALL STEP_FIZHI_FG ( myTime, myIter, myThid, deltaTtracer )
         CALL TIMER_STOP ('FIZHI               [FORWARD_STEP]',mythid)
        endif
#endif
C AMM

#ifdef ALLOW_EBM
        IF ( useEBM ) THEN
# ifdef ALLOW_DEBUG
         IF ( debugLevel .GE. debLevB )
     &    CALL DEBUG_CALL('EBM',myThid)
# endif
         CALL TIMER_START('EBM                [FORWARD_STEP]',mythid)
         CALL EBM_DRIVER ( myTime, myIter, myThid )
         CALL TIMER_STOP ('EBM                [FORWARD_STEP]',mythid)
        ENDIF
#endif

#ifdef ALLOW_DEBUG
      IF ( debugLevel .GE. debLevB ) 
     &    CALL DEBUG_CALL('THERMODYNAMICS',myThid)
#endif
        CALL TIMER_START('THERMODYNAMICS      [FORWARD_STEP]',mythid)
        CALL THERMODYNAMICS( myTime, myIter, myThid )
        CALL TIMER_STOP ('THERMODYNAMICS      [FORWARD_STEP]',mythid)

C--   do exchanges (needed for DYNAMICS) when using stagger time-step :
#ifdef ALLOW_DEBUG
      IF ( debugLevel .GE. debLevB ) 
     &    CALL DEBUG_CALL('DO_STAGGER_FIELDS_EXCH.',myThid)
#endif
        CALL TIMER_START('BLOCKING_EXCHANGES  [FORWARD_STEP]',myThid)
        CALL DO_STAGGER_FIELDS_EXCHANGES( myTime, myIter, myThid )
        CALL TIMER_STOP ('BLOCKING_EXCHANGES  [FORWARD_STEP]',myThid)

#ifdef ALLOW_SHAP_FILT
      IF (useSHAP_FILT .AND. 
     &     staggerTimeStep .AND. shap_filt_TrStagg ) THEN
#ifdef ALLOW_DEBUG
        IF ( debugLevel .GE. debLevB ) 
     &    CALL DEBUG_CALL('SHAP_FILT_APPLY_TS',myThid)
#endif
        CALL TIMER_START('SHAP_FILT           [FORWARD_STEP]',myThid)
        CALL SHAP_FILT_APPLY_TS(gT,gS,myTime+deltaT,myIter+1,myThid)
        CALL TIMER_STOP ('SHAP_FILT           [FORWARD_STEP]',myThid)
      ENDIF
#endif

#ifdef ALLOW_ZONAL_FILT
      IF (useZONAL_FILT .AND. 
     &     staggerTimeStep .AND. zonal_filt_TrStagg ) THEN
#ifdef ALLOW_DEBUG
        IF ( debugLevel .GE. debLevB ) 
     &    CALL DEBUG_CALL('ZONAL_FILT_APPLY_TS',myThid)
#endif
        CALL TIMER_START('ZONAL_FILT_APPLY    [FORWARD_STEP]',myThid)
        CALL ZONAL_FILT_APPLY_TS( gT, gS, myThid )
        CALL TIMER_STOP ('ZONAL_FILT_APPLY    [FORWARD_STEP]',myThid)
      ENDIF
#endif   

#ifdef COMPONENT_MODULE
       IF ( useCoupler .AND. .NOT.cpl_earlyExpImpCall ) THEN
C      Post coupling data that I export.
C      Read in coupling data that I import.
         myItP1 = myIter + 1
         CALL TIMER_START('CPL_EXPORT-IMPORT  [FORWARD_STEP]',myThid)
         CALL CPL_EXPORT_MY_DATA(       myItP1, myTime, myThid )
         CALL CPL_IMPORT_EXTERNAL_DATA( myItP1, myTime, myThid )
         CALL TIMER_STOP ('CPL_EXPORT-IMPORT  [FORWARD_STEP]',myThid)
# ifndef ALLOW_AIM
        IF ( useRealFreshWaterFlux ) THEN
         CALL OCN_APPLY_IMPORT( .FALSE., myTime, myIter, myThid )
        ENDIF
# endif
       ENDIF
#endif /* COMPONENT_MODULE */

C--   Step forward fields and calculate time tendency terms.
#ifndef ALLOW_AUTODIFF_TAMC
      IF ( momStepping ) THEN
#endif
#ifdef ALLOW_DEBUG
        IF ( debugLevel .GE. debLevB ) 
     &    CALL DEBUG_CALL('DYNAMICS',myThid)
#endif
        CALL TIMER_START('DYNAMICS            [FORWARD_STEP]',mythid)
        CALL DYNAMICS( myTime, myIter, myThid )
        CALL TIMER_STOP ('DYNAMICS            [FORWARD_STEP]',mythid)
#ifndef ALLOW_AUTODIFF_TAMC
      ENDIF
#endif

#ifdef ALLOW_NONHYDROSTATIC
C--   Step forward W field in N-H algorithm
      IF ( momStepping .AND. nonHydrostatic ) THEN
#ifdef ALLOW_DEBUG
          IF ( debugLevel .GE. debLevB ) 
     &     CALL DEBUG_CALL('CALC_GW',myThid)
#endif
         CALL TIMER_START('CALC_GW          [FORWARD_STEP]',myThid)
         CALL CALC_GW(myThid)
         CALL TIMER_STOP ('CALC_GW          [FORWARD_STEP]',myThid)
      ENDIF
#endif

#ifdef NONLIN_FRSURF
C--   update hfacC,W,S and recip_hFac according to etaH(n+1) :
      IF ( nonlinFreeSurf.GT.0) THEN
       IF ( select_rStar.GT.0 ) THEN
        CALL TIMER_START('UPDATE_R_STAR      [FORWARD_STEP]',myThid)
        CALL UPDATE_R_STAR( myTime, myIter, myThid )
        CALL TIMER_STOP ('UPDATE_R_STAR      [FORWARD_STEP]',myThid)
       ELSE
        CALL TIMER_START('UPDATE_SURF_DR     [FORWARD_STEP]',myThid)
        CALL UPDATE_SURF_DR( myTime, myIter, myThid )
        CALL TIMER_STOP ('UPDATE_SURF_DR     [FORWARD_STEP]',myThid)
       ENDIF
      ENDIF
C-    update also CG2D matrix (and preconditioner)
      IF ( momStepping .AND. nonlinFreeSurf.GT.2 ) THEN
        CALL TIMER_START('UPDATE_CG2D        [FORWARD_STEP]',myThid)
        CALL UPDATE_CG2D( myTime, myIter, myThid )
        CALL TIMER_STOP ('UPDATE_CG2D        [FORWARD_STEP]',myThid)
      ENDIF
#endif

C--   Apply Filters to u*,v* before SOLVE_FOR_PRESSURE
#ifdef ALLOW_SHAP_FILT
      IF (useSHAP_FILT .AND. shap_filt_uvStar) THEN
        CALL TIMER_START('SHAP_FILT           [FORWARD_STEP]',myThid)
        IF (implicDiv2Dflow.LT.1.) THEN
C--   Explicit+Implicit part of the Barotropic Flow Divergence
C      => Filtering of uVel,vVel is necessary
          CALL SHAP_FILT_APPLY_UV( uVel,vVel,
     &                             myTime+deltaT, myIter+1, myThid )
        ENDIF
        CALL SHAP_FILT_APPLY_UV( gU,gV,myTime+deltaT,myIter+1,myThid)
        CALL TIMER_STOP ('SHAP_FILT           [FORWARD_STEP]',myThid)
      ENDIF
#endif
#ifdef ALLOW_ZONAL_FILT
      IF (useZONAL_FILT .AND. zonal_filt_uvStar) THEN
        CALL TIMER_START('ZONAL_FILT_APPLY    [FORWARD_STEP]',myThid)
        IF (implicDiv2Dflow.LT.1.) THEN
C--   Explicit+Implicit part of the Barotropic Flow Divergence
C      => Filtering of uVel,vVel is necessary
          CALL ZONAL_FILT_APPLY_UV( uVel, vVel, myThid )
        ENDIF
        CALL ZONAL_FILT_APPLY_UV( gU, gV, myThid )
        CALL TIMER_STOP ('ZONAL_FILT_APPLY    [FORWARD_STEP]',myThid)
      ENDIF
#endif  

C--   Solve elliptic equation(s).
C     Two-dimensional only for conventional hydrostatic or 
C     three-dimensional for non-hydrostatic and/or IGW scheme.
      IF ( momStepping ) THEN
      CALL TIMER_START('SOLVE_FOR_PRESSURE  [FORWARD_STEP]',myThid)
      CALL SOLVE_FOR_PRESSURE(myTime, myIter, myThid)
      CALL TIMER_STOP ('SOLVE_FOR_PRESSURE  [FORWARD_STEP]',myThid)
      ENDIF

#ifdef ALLOW_AUTODIFF_TAMC
cph This is needed because convective_adjustment calls
cph find_rho which may use pressure()
CADJ STORE totphihyd  = comlev1, key = ikey_dynamics
#endif
C--   Correct divergence in flow field and cycle time-stepping
C     arrays (for all fields) ; update time-counter
      myIter = nIter0 + iLoop
      myTime = startTime + deltaTClock * float(iLoop)
      CALL TIMER_START('THE_CORRECTION_STEP [FORWARD_STEP]',myThid)
      CALL THE_CORRECTION_STEP(myTime, myIter, myThid)
      CALL TIMER_STOP ('THE_CORRECTION_STEP [FORWARD_STEP]',myThid)

C--   Do "blocking" sends and receives for tendency "overlap" terms
c     CALL TIMER_START('BLOCKING_EXCHANGES  [FORWARD_STEP]',myThid)
c     CALL DO_GTERM_BLOCKING_EXCHANGES( myThid )
c     CALL TIMER_STOP ('BLOCKING_EXCHANGES  [FORWARD_STEP]',myThid)

C--   Do "blocking" sends and receives for field "overlap" terms
      CALL TIMER_START('BLOCKING_EXCHANGES  [FORWARD_STEP]',myThid)
      CALL DO_FIELDS_BLOCKING_EXCHANGES( myThid )
      CALL TIMER_STOP ('BLOCKING_EXCHANGES  [FORWARD_STEP]',myThid)

cswdptr -- add for seperate timestepping of chemical/biological/forcing
cswdptr    of ptracers ---
#ifdef ALLOW_GCHEM
ceh3 This is broken -- this ifdef should not be visible!
#ifdef PTRACERS_SEPARATE_FORCING
ceh3 needs an IF ( use GCHEM ) THEN
        call GCHEM_FORCING_SEP( myTime,myIter,myThid )
#endif /* PTRACERS_SEPARATE_FORCING */
#endif /* ALLOW_GCHEM */
cswdptr -- end add ---

C AMM
#ifdef ALLOW_GRIDALT
        if (useGRIDALT) then
         CALL GRIDALT_UPDATE(myThid)
        endif
#endif
C AMM

C AMM
#ifdef ALLOW_FIZHI
        if( useFIZHI) then
         CALL TIMER_START('FIZHI               [FORWARD_STEP]',mythid)
         CALL STEP_FIZHI_CORR ( myTime, myIter, myThid )
         CALL TIMER_STOP('FIZHI               [FORWARD_STEP]',mythid)
        endif
#endif
C AMM

#ifdef ALLOW_FLT
C--   Calculate float trajectories
      IF (useFLT) THEN
        CALL TIMER_START('FLOATS            [FORWARD_STEP]',myThid)
        CALL FLT_MAIN(myIter,myTime, myThid)
        CALL TIMER_STOP ('FLOATS            [FORWARD_STEP]',myThid)
      ENDIF
#endif

#ifdef ALLOW_MONITOR
C--   Check status of solution (statistics, cfl, etc...)
      CALL TIMER_START('MONITOR             [FORWARD_STEP]',myThid)
      CALL MONITOR( myIter, myTime, myThid )
      CALL TIMER_STOP ('MONITOR             [FORWARD_STEP]',myThid)
#endif /* ALLOW_MONITOR */

C AMM  -- Diagnostics package
#ifdef ALLOW_DIAGNOSTICS

       if(usediagnostics)then
        call diagnostics_fill_state(myThid)
       endif

# ifdef ALLOW_PTRACERS
      if(useptracers)then
       call diagnostics_fill_ptracers(myThid)
      endif
# endif

#endif
C AMM

C--   Do IO if needed.
      CALL TIMER_START('DO_THE_MODEL_IO     [FORWARD_STEP]',myThid)
      CALL DO_THE_MODEL_IO( myTime, myIter, myThid )
      CALL TIMER_STOP ('DO_THE_MODEL_IO     [FORWARD_STEP]',myThid)

C--   Save state for restarts
C     Note:    (jmc: is it still the case after ckp35 ?)
C     =====
C     Because of the ordering of the timestepping code and
C     tendency term code at end of loop model arrays hold
C     U,V,T,S  at "time-level" N but gu, gv, gs, gt, guNM1,... 
C     at "time-level" N+1/2 (guNM1 at "time-level" N+1/2 is 
C     gu at "time-level" N-1/2) and etaN at "time-level" N+1/2.
C      where N = I+timeLevBase-1
C     Thus a checkpoint contains U.0000000000, GU.0000000001 and 
C     etaN.0000000001 in the indexing scheme used for the model 
C     "state" files. This example is referred to as a checkpoint 
C     at time level 1 
      CALL TIMER_START('WRITE_CHECKPOINT    [FORWARD_STEP]',myThid)
      CALL PACKAGES_WRITE_PICKUP(
     I               .FALSE., myTime, myIter, myThid )
      CALL WRITE_CHECKPOINT(
     I               .FALSE., myTime, myIter, myThid )   
      CALL TIMER_STOP ('WRITE_CHECKPOINT    [FORWARD_STEP]',myThid)

#ifdef ALLOW_DEBUG
      IF ( debugLevel .GE. debLevB ) 
     &    CALL DEBUG_LEAVE('FORWARD_STEP',myThid)
#endif

      RETURN
      END
1	C $Header: /u/gcmpack/MITgcm/model/src/forward_step.F,v 1.92 2004/05/14 21:08:28 heimbach Exp $
2	C $Name: $
3
4	#include "PACKAGES_CONFIG.h"
5	#include "CPP_OPTIONS.h"
6
7	cswdptr -- add --
8	#ifdef ALLOW_GCHEM
9	# include "GCHEM_OPTIONS.h"
10	#endif
11	cswdptr -- end add ---
12
13	CBOP
14	C !ROUTINE: FORWARD_STEP
15	C !INTERFACE:
16	SUBROUTINE FORWARD_STEP( iloop, myTime, myIter, myThid )
17
18	C !DESCRIPTION: \bv
19	C *==================================================================
20	C \| SUBROUTINE forward_step
21	C \| o Run the ocean model and, optionally, evaluate a cost function.
22	C *==================================================================
23	C \|
24	C \| THE_MAIN_LOOP is the toplevel routine for the Tangent Linear and
25	C \| Adjoint Model Compiler (TAMC). For this purpose the initialization
26	C \| of the model was split into two parts. Those parameters that do
27	C \| not depend on a specific model run are set in INITIALISE_FIXED,
28	C \| whereas those that do depend on the specific realization are
29	C \| initialized in INITIALISE_VARIA.
30	C \|
31	C *==================================================================
32	C \ev
33
34	C !USES:
35	IMPLICIT NONE
36	C == Global variables ==
37	#include "SIZE.h"
38	#include "EEPARAMS.h"
39	#include "PARAMS.h"
40	#include "DYNVARS.h"
41
42	#ifdef ALLOW_SHAP_FILT
43	# include "SHAP_FILT.h"
44	#endif
45	#ifdef ALLOW_ZONAL_FILT
46	# include "ZONAL_FILT.h"
47	#endif
48	#ifdef COMPONENT_MODULE
49	# include "CPL_PARAMS.h"
50	#endif
51
52	#ifdef ALLOW_AUTODIFF_TAMC
53	# include "FFIELDS.h"
54
55	# ifdef ALLOW_NONHYDROSTATIC
56	# include "CG3D.h"
57	# endif
58
59	# include "tamc.h"
60	# include "ctrl.h"
61	# include "ctrl_dummy.h"
62	# include "cost.h"
63	# include "EOS.h"
64	# ifdef ALLOW_EXF
65	# include "exf_fields.h"
66	# include "exf_clim_fields.h"
67	# ifdef ALLOW_BULKFORMULAE
68	# include "exf_constants.h"
69	# endif
70	# endif
71	# ifdef ALLOW_OBCS
72	# include "OBCS.h"
73	# endif
74	# ifdef ALLOW_PTRACERS
75	# include "PTRACERS.h"
76	# endif
77	# ifdef ALLOW_CD_CODE
78	# include "CD_CODE_VARS.h"
79	# endif
80	# ifdef ALLOW_EBM
81	# include "EBM.h"
82	# endif
83	#endif /* ALLOW_AUTODIFF_TAMC */
84
85	C !LOCAL VARIABLES:
86	C == Routine arguments ==
87	C note: under the multi-threaded model myiter and
88	C mytime are local variables passed around as routine
89	C arguments. Although this is fiddly it saves the need to
90	C impose additional synchronisation points when they are
91	C updated.
92	C myIter - iteration counter for this thread
93	C myTime - time counter for this thread
94	C myThid - thread number for this instance of the routine.
95	INTEGER iloop
96	INTEGER myThid
97	INTEGER myIter
98	_RL myTime
99
100	C == Local variables ==
101	integer i,L
102	INTEGER myItP1
103	CEOP
104
105	#ifdef ALLOW_DEBUG
106	IF ( debugLevel .GE. debLevB )
107	& CALL DEBUG_ENTER('FORWARD_STEP',myThid)
108	#endif
109
110	#ifdef ALLOW_AUTODIFF_TAMC
111	C-- Reset the model iteration counter and the model time.
112	myiter = nIter0 + (iloop-1)
113	mytime = startTime + float(iloop-1)*deltaTclock
114	#endif
115
116	#if (defined (ALLOW_AUTODIFF_TAMC) && defined (ALLOW_AUTODIFF_MONITOR))
117	C Include call to a dummy routine. Its adjoint will be
118	C called at the proper place in the adjoint code.
119	C The adjoint routine will print out adjoint values
120	C if requested. The location of the call is important,
121	C it has to be after the adjoint of the exchanges
122	C (DO_GTERM_BLOCKING_EXCHANGES).
123	CALL DUMMY_IN_STEPPING( myTime, myIter, myThid )
124	cph I've commented this line since it may conflict with MITgcm's adjoint
125	cph However, need to check whether that's still consistent
126	cph with the ecco-branch (it should).
127	cph CALL DO_FIELDS_BLOCKING_EXCHANGES( myThid )
128	#endif
129
130	#ifdef EXACT_CONSERV
131	IF (exactConserv) THEN
132	C-- Update etaH(n+1) :
133	CALL TIMER_START('UPDATE_ETAH [FORWARD_STEP]',mythid)
134	CALL UPDATE_ETAH( myTime, myIter, myThid )
135	CALL TIMER_STOP ('UPDATE_ETAH [FORWARD_STEP]',mythid)
136	ENDIF
137	#endif /* EXACT_CONSERV */
138
139	#ifdef NONLIN_FRSURF
140	IF ( select_rStar.NE.0 ) THEN
141	C-- r* : compute the future level thickness according to etaH(n+1)
142	CALL TIMER_START('CALC_R_STAR [FORWARD_STEP]',mythid)
143	CALL CALC_R_STAR(etaH, myTime, myIter, myThid )
144	CALL TIMER_STOP ('CALC_R_STAR [FORWARD_STEP]',mythid)
145	ELSEIF ( nonlinFreeSurf.GT.0) THEN
146	C-- compute the future surface level thickness according to etaH(n+1)
147	CALL TIMER_START('CALC_SURF_DR [FORWARD_STEP]',mythid)
148	CALL CALC_SURF_DR(etaH, myTime, myIter, myThid )
149	CALL TIMER_STOP ('CALC_SURF_DR [FORWARD_STEP]',mythid)
150	ENDIF
151	#endif /* NONLIN_FRSURF */
152
153	#ifdef ALLOW_AUTODIFF_TAMC
154	c**************************************
155	#include "checkpoint_lev1_directives.h"
156	c**************************************
157	#endif
158
159	C-- Call external forcing package
160	#ifdef ALLOW_BULK_FORCE
161	IF ( useBulkForce ) THEN
162	#ifdef ALLOW_DEBUG
163	IF ( debugLevel .GE. debLevB )
164	& CALL DEBUG_CALL('BULKF_FIELDS_LOAD',myThid)
165	#endif
166	CALL TIMER_START('BULKF_FORCING [FORWARD_STEP]',mythid)
167	C- load all forcing fields at current time
168	CALL BULKF_FIELDS_LOAD( myTime, myIter, myThid )
169	C- calculate qnet and empmr (and wind stress)
170	CALL BULKF_FORCING( myTime, myIter, myThid )
171	CALL TIMER_STOP ('BULKF_FORCING [FORWARD_STEP]',mythid)
172	ELSE
173	#endif /* ALLOW_BULK_FORCE */
174
175	# ifdef ALLOW_EXF
176	# ifdef ALLOW_DEBUG
177	IF ( debugLevel .GE. debLevB )
178	& CALL DEBUG_CALL('EXF_GETFORCING',myThid)
179	# endif
180	CALL TIMER_START('EXF_GETFORCING [FORWARD_STEP]',mythid)
181	CALL EXF_GETFORCING( mytime, myiter, mythid )
182	CALL TIMER_STOP ('EXF_GETFORCING [FORWARD_STEP]',mythid)
183	# else /* ALLOW_EXF undef */
184	cph The following IF-statement creates an additional dependency
185	cph for the forcing fields requiring additional storing.
186	cph Therefore, the IF-statement will be put between CPP-OPTIONS,
187	cph assuming that ALLOW_SEAICE has not yet been differentiated.
188	# if (defined (ALLOW_SEAICE) \|\| defined (ALLOW_EBM))
189	IF ( .NOT. useSEAICE .AND. .NOT. useEBM ) THEN
190	# endif
191	#ifdef ALLOW_DEBUG
192	IF ( debugLevel .GE. debLevB )
193	& CALL DEBUG_CALL('EXTERNAL_FIELDS_LOAD',myThid)
194	#endif
195	CALL TIMER_START('EXTERNAL_FIELDS_LOAD[FORWARD_STEP]',mythid)
196	CALL EXTERNAL_FIELDS_LOAD( mytime, myiter, mythid )
197	CALL TIMER_STOP ('EXTERNAL_FIELDS_LOAD[FORWARD_STEP]',mythid)
198	# if (defined (ALLOW_SEAICE) \|\| defined (ALLOW_EBM))
199	ENDIF
200	# endif
201	# endif /* ALLOW_EXF */
202	#ifdef ALLOW_BULK_FORCE
203	C-- end of if/else block useBulfforce --
204	ENDIF
205	#endif /* ALLOW_BULK_FORCE */
206
207	#ifdef ALLOW_AUTODIFF
208	c-- Add control vector for forcing and parameter fields
209	if ( myiter .EQ. nIter0 )
210	& CALL CTRL_MAP_FORCING (mythid)
211	#endif
212
213	#ifdef ALLOW_THSICE
214	IF ( useThSIce .AND. buoyancyRelation(1:7) .EQ. 'OCEANIC' ) THEN
215	#ifdef ALLOW_DEBUG
216	IF ( debugLevel .GE. debLevB )
217	& CALL DEBUG_CALL('THSICE_MAIN',myThid)
218	#endif
219	C-- Step forward Therm.Sea-Ice variables
220	C and modify forcing terms including effects from ice
221	CALL TIMER_START('THSICE_MAIN [FORWARD_STEP]', myThid)
222	CALL THSICE_MAIN( myTime, myIter, myThid )
223	CALL TIMER_STOP( 'THSICE_MAIN [FORWARD_STEP]', myThid)
224	ENDIF
225	#endif /* ALLOW_THSICE */
226
227	# ifdef ALLOW_SEAICE
228	C-- Call sea ice model to compute forcing/external data fields. In
229	C addition to computing prognostic sea-ice variables and diagnosing the
230	C forcing/external data fields that drive the ocean model, SEAICE_MODEL
231	C also sets theta to the freezing point under sea-ice. The implied
232	C surface heat flux is then stored in variable surfaceTendencyTice,
233	C which is needed by KPP package (kpp_calc.F and kpp_transport_t.F)
234	C to diagnose surface buoyancy fluxes and for the non-local transport
235	C term. Because this call precedes model thermodynamics, temperature
236	C under sea-ice may not be "exactly" at the freezing point by the time
237	C theta is dumped or time-averaged.
238	IF ( useSEAICE ) THEN
239	#ifdef ALLOW_DEBUG
240	IF ( debugLevel .GE. debLevB )
241	& CALL DEBUG_CALL('SEAICE_MODEL',myThid)
242	#endif
243	CALL TIMER_START('SEAICE_MODEL [FORWARD_STEP]',myThid)
244	CALL SEAICE_MODEL( myTime, myIter, myThid )
245	CALL TIMER_STOP ('SEAICE_MODEL [FORWARD_STEP]',myThid)
246	ENDIF
247	# endif /* ALLOW_SEAICE */
248
249	C-- Freeze water at the surface
250	#ifdef ALLOW_AUTODIFF_TAMC
251	CADJ STORE theta = comlev1, key = ikey_dynamics
252	#endif
253	IF ( allowFreezing .AND. .NOT. useSEAICE
254	& .AND. .NOT. useThSIce ) THEN
255	CALL FREEZE_SURFACE( myTime, myIter, myThid )
256	ENDIF
257
258	#ifdef ALLOW_AUTODIFF_TAMC
259	# ifdef ALLOW_PTRACERS
260	cph this replaces _bibj storing of ptracer within thermodynamics
261	CADJ STORE ptracer = comlev1, key = ikey_dynamics
262	# endif
263	#endif
264
265	#ifdef ALLOW_PTRACERS
266	# ifdef ALLOW_GCHEM
267	CALL GCHEM_FIELDS_LOAD( mytime, myiter, mythid )
268	# endif
269	#endif
270
271	#ifdef COMPONENT_MODULE
272	IF ( useCoupler .AND. cpl_earlyExpImpCall ) THEN
273	C Post coupling data that I export.
274	C Read in coupling data that I import.
275	CALL TIMER_START('CPL_EXPORT-IMPORT [FORWARD_STEP]',myThid)
276	CALL CPL_EXPORT_MY_DATA( myIter, myTime, myThid )
277	CALL CPL_IMPORT_EXTERNAL_DATA( myIter, myTime, myThid )
278	CALL TIMER_STOP ('CPL_EXPORT-IMPORT [FORWARD_STEP]',myThid)
279	ENDIF
280	# ifndef ALLOW_AIM
281	C jmc: don't know precisely where to put this call. leave it here for now.
282	IF ( useCoupler ) THEN
283	CALL OCN_APPLY_IMPORT( .TRUE., myTime, myIter, myThid )
284	ENDIF
285	# endif
286	#endif /* COMPONENT_MODULE */
287
288	C-- Step forward fields and calculate time tendency terms.
289
290	C AMM
291	#ifdef ALLOW_FIZHI
292	if( useFIZHI) then
293	CALL TIMER_START('FIZHI [FORWARD_STEP]',mythid)
294	CALL UPDATE_OCEAN_EXPORTS ( myTime, myIter, myThid )
295	CALL UPDATE_EARTH_EXPORTS ( myTime, myIter, myThid )
296	CALL UPDATE_CHEMISTRY_EXPORTS ( myTime, myIter, myThid )
297	CALL FIZHI_WRAPPER ( myTime, myIter, myThid )
298	CALL STEP_FIZHI_FG ( myTime, myIter, myThid, deltaTtracer )
299	CALL TIMER_STOP ('FIZHI [FORWARD_STEP]',mythid)
300	endif
301	#endif
302	C AMM
303
304	#ifdef ALLOW_EBM
305	IF ( useEBM ) THEN
306	# ifdef ALLOW_DEBUG
307	IF ( debugLevel .GE. debLevB )
308	& CALL DEBUG_CALL('EBM',myThid)
309	# endif
310	CALL TIMER_START('EBM [FORWARD_STEP]',mythid)
311	CALL EBM_DRIVER ( myTime, myIter, myThid )
312	CALL TIMER_STOP ('EBM [FORWARD_STEP]',mythid)
313	ENDIF
314	#endif
315
316	#ifdef ALLOW_DEBUG
317	IF ( debugLevel .GE. debLevB )
318	& CALL DEBUG_CALL('THERMODYNAMICS',myThid)
319	#endif
320	CALL TIMER_START('THERMODYNAMICS [FORWARD_STEP]',mythid)
321	CALL THERMODYNAMICS( myTime, myIter, myThid )
322	CALL TIMER_STOP ('THERMODYNAMICS [FORWARD_STEP]',mythid)
323
324	C-- do exchanges (needed for DYNAMICS) when using stagger time-step :
325	#ifdef ALLOW_DEBUG
326	IF ( debugLevel .GE. debLevB )
327	& CALL DEBUG_CALL('DO_STAGGER_FIELDS_EXCH.',myThid)
328	#endif
329	CALL TIMER_START('BLOCKING_EXCHANGES [FORWARD_STEP]',myThid)
330	CALL DO_STAGGER_FIELDS_EXCHANGES( myTime, myIter, myThid )
331	CALL TIMER_STOP ('BLOCKING_EXCHANGES [FORWARD_STEP]',myThid)
332
333	#ifdef ALLOW_SHAP_FILT
334	IF (useSHAP_FILT .AND.
335	& staggerTimeStep .AND. shap_filt_TrStagg ) THEN
336	#ifdef ALLOW_DEBUG
337	IF ( debugLevel .GE. debLevB )
338	& CALL DEBUG_CALL('SHAP_FILT_APPLY_TS',myThid)
339	#endif
340	CALL TIMER_START('SHAP_FILT [FORWARD_STEP]',myThid)
341	CALL SHAP_FILT_APPLY_TS(gT,gS,myTime+deltaT,myIter+1,myThid)
342	CALL TIMER_STOP ('SHAP_FILT [FORWARD_STEP]',myThid)
343	ENDIF
344	#endif
345
346	#ifdef ALLOW_ZONAL_FILT
347	IF (useZONAL_FILT .AND.
348	& staggerTimeStep .AND. zonal_filt_TrStagg ) THEN
349	#ifdef ALLOW_DEBUG
350	IF ( debugLevel .GE. debLevB )
351	& CALL DEBUG_CALL('ZONAL_FILT_APPLY_TS',myThid)
352	#endif
353	CALL TIMER_START('ZONAL_FILT_APPLY [FORWARD_STEP]',myThid)
354	CALL ZONAL_FILT_APPLY_TS( gT, gS, myThid )
355	CALL TIMER_STOP ('ZONAL_FILT_APPLY [FORWARD_STEP]',myThid)
356	ENDIF
357	#endif
358
359	#ifdef COMPONENT_MODULE
360	IF ( useCoupler .AND. .NOT.cpl_earlyExpImpCall ) THEN
361	C Post coupling data that I export.
362	C Read in coupling data that I import.
363	myItP1 = myIter + 1
364	CALL TIMER_START('CPL_EXPORT-IMPORT [FORWARD_STEP]',myThid)
365	CALL CPL_EXPORT_MY_DATA( myItP1, myTime, myThid )
366	CALL CPL_IMPORT_EXTERNAL_DATA( myItP1, myTime, myThid )
367	CALL TIMER_STOP ('CPL_EXPORT-IMPORT [FORWARD_STEP]',myThid)
368	# ifndef ALLOW_AIM
369	IF ( useRealFreshWaterFlux ) THEN
370	CALL OCN_APPLY_IMPORT( .FALSE., myTime, myIter, myThid )
371	ENDIF
372	# endif
373	ENDIF
374	#endif /* COMPONENT_MODULE */
375
376	C-- Step forward fields and calculate time tendency terms.
377	#ifndef ALLOW_AUTODIFF_TAMC
378	IF ( momStepping ) THEN
379	#endif
380	#ifdef ALLOW_DEBUG
381	IF ( debugLevel .GE. debLevB )
382	& CALL DEBUG_CALL('DYNAMICS',myThid)
383	#endif
384	CALL TIMER_START('DYNAMICS [FORWARD_STEP]',mythid)
385	CALL DYNAMICS( myTime, myIter, myThid )
386	CALL TIMER_STOP ('DYNAMICS [FORWARD_STEP]',mythid)
387	#ifndef ALLOW_AUTODIFF_TAMC
388	ENDIF
389	#endif
390
391	#ifdef ALLOW_NONHYDROSTATIC
392	C-- Step forward W field in N-H algorithm
393	IF ( momStepping .AND. nonHydrostatic ) THEN
394	#ifdef ALLOW_DEBUG
395	IF ( debugLevel .GE. debLevB )
396	& CALL DEBUG_CALL('CALC_GW',myThid)
397	#endif
398	CALL TIMER_START('CALC_GW [FORWARD_STEP]',myThid)
399	CALL CALC_GW(myThid)
400	CALL TIMER_STOP ('CALC_GW [FORWARD_STEP]',myThid)
401	ENDIF
402	#endif
403
404	#ifdef NONLIN_FRSURF
405	C-- update hfacC,W,S and recip_hFac according to etaH(n+1) :
406	IF ( nonlinFreeSurf.GT.0) THEN
407	IF ( select_rStar.GT.0 ) THEN
408	CALL TIMER_START('UPDATE_R_STAR [FORWARD_STEP]',myThid)
409	CALL UPDATE_R_STAR( myTime, myIter, myThid )
410	CALL TIMER_STOP ('UPDATE_R_STAR [FORWARD_STEP]',myThid)
411	ELSE
412	CALL TIMER_START('UPDATE_SURF_DR [FORWARD_STEP]',myThid)
413	CALL UPDATE_SURF_DR( myTime, myIter, myThid )
414	CALL TIMER_STOP ('UPDATE_SURF_DR [FORWARD_STEP]',myThid)
415	ENDIF
416	ENDIF
417	C- update also CG2D matrix (and preconditioner)
418	IF ( momStepping .AND. nonlinFreeSurf.GT.2 ) THEN
419	CALL TIMER_START('UPDATE_CG2D [FORWARD_STEP]',myThid)
420	CALL UPDATE_CG2D( myTime, myIter, myThid )
421	CALL TIMER_STOP ('UPDATE_CG2D [FORWARD_STEP]',myThid)
422	ENDIF
423	#endif
424
425	C-- Apply Filters to u,v before SOLVE_FOR_PRESSURE
426	#ifdef ALLOW_SHAP_FILT
427	IF (useSHAP_FILT .AND. shap_filt_uvStar) THEN
428	CALL TIMER_START('SHAP_FILT [FORWARD_STEP]',myThid)
429	IF (implicDiv2Dflow.LT.1.) THEN
430	C-- Explicit+Implicit part of the Barotropic Flow Divergence
431	C => Filtering of uVel,vVel is necessary
432	CALL SHAP_FILT_APPLY_UV( uVel,vVel,
433	& myTime+deltaT, myIter+1, myThid )
434	ENDIF
435	CALL SHAP_FILT_APPLY_UV( gU,gV,myTime+deltaT,myIter+1,myThid)
436	CALL TIMER_STOP ('SHAP_FILT [FORWARD_STEP]',myThid)
437	ENDIF
438	#endif
439	#ifdef ALLOW_ZONAL_FILT
440	IF (useZONAL_FILT .AND. zonal_filt_uvStar) THEN
441	CALL TIMER_START('ZONAL_FILT_APPLY [FORWARD_STEP]',myThid)
442	IF (implicDiv2Dflow.LT.1.) THEN
443	C-- Explicit+Implicit part of the Barotropic Flow Divergence
444	C => Filtering of uVel,vVel is necessary
445	CALL ZONAL_FILT_APPLY_UV( uVel, vVel, myThid )
446	ENDIF
447	CALL ZONAL_FILT_APPLY_UV( gU, gV, myThid )
448	CALL TIMER_STOP ('ZONAL_FILT_APPLY [FORWARD_STEP]',myThid)
449	ENDIF
450	#endif
451
452	C-- Solve elliptic equation(s).
453	C Two-dimensional only for conventional hydrostatic or
454	C three-dimensional for non-hydrostatic and/or IGW scheme.
455	IF ( momStepping ) THEN
456	CALL TIMER_START('SOLVE_FOR_PRESSURE [FORWARD_STEP]',myThid)
457	CALL SOLVE_FOR_PRESSURE(myTime, myIter, myThid)
458	CALL TIMER_STOP ('SOLVE_FOR_PRESSURE [FORWARD_STEP]',myThid)
459	ENDIF
460
461	#ifdef ALLOW_AUTODIFF_TAMC
462	cph This is needed because convective_adjustment calls
463	cph find_rho which may use pressure()
464	CADJ STORE totphihyd = comlev1, key = ikey_dynamics
465	#endif
466	C-- Correct divergence in flow field and cycle time-stepping
467	C arrays (for all fields) ; update time-counter
468	myIter = nIter0 + iLoop
469	myTime = startTime + deltaTClock * float(iLoop)
470	CALL TIMER_START('THE_CORRECTION_STEP [FORWARD_STEP]',myThid)
471	CALL THE_CORRECTION_STEP(myTime, myIter, myThid)
472	CALL TIMER_STOP ('THE_CORRECTION_STEP [FORWARD_STEP]',myThid)
473
474	C-- Do "blocking" sends and receives for tendency "overlap" terms
475	c CALL TIMER_START('BLOCKING_EXCHANGES [FORWARD_STEP]',myThid)
476	c CALL DO_GTERM_BLOCKING_EXCHANGES( myThid )
477	c CALL TIMER_STOP ('BLOCKING_EXCHANGES [FORWARD_STEP]',myThid)
478
479	C-- Do "blocking" sends and receives for field "overlap" terms
480	CALL TIMER_START('BLOCKING_EXCHANGES [FORWARD_STEP]',myThid)
481	CALL DO_FIELDS_BLOCKING_EXCHANGES( myThid )
482	CALL TIMER_STOP ('BLOCKING_EXCHANGES [FORWARD_STEP]',myThid)
483
484	cswdptr -- add for seperate timestepping of chemical/biological/forcing
485	cswdptr of ptracers ---
486	#ifdef ALLOW_GCHEM
487	ceh3 This is broken -- this ifdef should not be visible!
488	#ifdef PTRACERS_SEPARATE_FORCING
489	ceh3 needs an IF ( use GCHEM ) THEN
490	call GCHEM_FORCING_SEP( myTime,myIter,myThid )
491	#endif /* PTRACERS_SEPARATE_FORCING */
492	#endif /* ALLOW_GCHEM */
493	cswdptr -- end add ---
494
495	C AMM
496	#ifdef ALLOW_GRIDALT
497	if (useGRIDALT) then
498	CALL GRIDALT_UPDATE(myThid)
499	endif
500	#endif
501	C AMM
502
503	C AMM
504	#ifdef ALLOW_FIZHI
505	if( useFIZHI) then
506	CALL TIMER_START('FIZHI [FORWARD_STEP]',mythid)
507	CALL STEP_FIZHI_CORR ( myTime, myIter, myThid )
508	CALL TIMER_STOP('FIZHI [FORWARD_STEP]',mythid)
509	endif
510	#endif
511	C AMM
512
513	#ifdef ALLOW_FLT
514	C-- Calculate float trajectories
515	IF (useFLT) THEN
516	CALL TIMER_START('FLOATS [FORWARD_STEP]',myThid)
517	CALL FLT_MAIN(myIter,myTime, myThid)
518	CALL TIMER_STOP ('FLOATS [FORWARD_STEP]',myThid)
519	ENDIF
520	#endif
521
522	#ifdef ALLOW_MONITOR
523	C-- Check status of solution (statistics, cfl, etc...)
524	CALL TIMER_START('MONITOR [FORWARD_STEP]',myThid)
525	CALL MONITOR( myIter, myTime, myThid )
526	CALL TIMER_STOP ('MONITOR [FORWARD_STEP]',myThid)
527	#endif /* ALLOW_MONITOR */
528
529	C AMM -- Diagnostics package
530	#ifdef ALLOW_DIAGNOSTICS
531
532	if(usediagnostics)then
533	call diagnostics_fill_state(myThid)
534	endif
535
536	# ifdef ALLOW_PTRACERS
537	if(useptracers)then
538	call diagnostics_fill_ptracers(myThid)
539	endif
540	# endif
541
542	#endif
543	C AMM
544
545	C-- Do IO if needed.
546	CALL TIMER_START('DO_THE_MODEL_IO [FORWARD_STEP]',myThid)
547	CALL DO_THE_MODEL_IO( myTime, myIter, myThid )
548	CALL TIMER_STOP ('DO_THE_MODEL_IO [FORWARD_STEP]',myThid)
549
550	C-- Save state for restarts
551	C Note: (jmc: is it still the case after ckp35 ?)
552	C =====
553	C Because of the ordering of the timestepping code and
554	C tendency term code at end of loop model arrays hold
555	C U,V,T,S at "time-level" N but gu, gv, gs, gt, guNM1,...
556	C at "time-level" N+1/2 (guNM1 at "time-level" N+1/2 is
557	C gu at "time-level" N-1/2) and etaN at "time-level" N+1/2.
558	C where N = I+timeLevBase-1
559	C Thus a checkpoint contains U.0000000000, GU.0000000001 and
560	C etaN.0000000001 in the indexing scheme used for the model
561	C "state" files. This example is referred to as a checkpoint
562	C at time level 1
563	CALL TIMER_START('WRITE_CHECKPOINT [FORWARD_STEP]',myThid)
564	CALL PACKAGES_WRITE_PICKUP(
565	I .FALSE., myTime, myIter, myThid )
566	CALL WRITE_CHECKPOINT(
567	I .FALSE., myTime, myIter, myThid )
568	CALL TIMER_STOP ('WRITE_CHECKPOINT [FORWARD_STEP]',myThid)
569
570	#ifdef ALLOW_DEBUG
571	IF ( debugLevel .GE. debLevB )
572	& CALL DEBUG_LEAVE('FORWARD_STEP',myThid)
573	#endif
574
575	RETURN
576	END