model/src/forward_step.F

C $Header: /u/gcmpack/MITgcm/model/src/forward_step.F,v 1.35 2002/10/07 16:24:45 jmc Exp $
C $Name:  $

#include "CPP_OPTIONS.h"

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"
#include "FFIELDS.h"

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

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

#ifdef ALLOW_AUTODIFF_TAMC
# include "tamc.h"
# include "ctrl.h"
# include "ctrl_dummy.h"
# include "cost.h"
# ifdef INCLUDE_EXTERNAL_FORCING_PACKAGE
#  include "exf_fields.h"
#  ifdef ALLOW_BULKFORMULAE
#   include "exf_constants.h"
#  endif
# endif
# ifdef ALLOW_OBCS
#  include "OBCS.h"
# endif
#endif

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
      INTEGER bi,bj

CEOP


#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 )
        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
C--   compute the future surface level thickness
C      according to etaH(n+1) 
        IF ( nonlinFreeSurf.GT.0) THEN
          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 */

C--     Load forcing/external data fields.
#ifdef ALLOW_AUTODIFF_TAMC
c**************************************
#include "checkpoint_lev1_directives.h"
c**************************************
#endif
#ifdef INCLUDE_EXTERNAL_FORCING_PACKAGE
C       NOTE, that although the exf package is part of the
C       distribution, it is not currently maintained, i.e.
C       exf is disabled by default in genmake.
        IF ( .not. useSEAICE ) THEN 
         CALL TIMER_START('EXF_GETFORCING     [FORWARD_STEP]',mythid)
         CALL EXF_GETFORCING( mytime, myiter, mythid )
         CALL TIMER_STOP ('EXF_GETFORCING     [FORWARD_STEP]',mythid)
        ENDIF
#else
        IF ( .not. useSEAICE ) THEN 
         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)
        ENDIF
#endif /* INCLUDE_EXTERNAL_FORCING_PACKAGE */

#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
         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--     Step forward fields and calculate time tendency terms.
        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 :
        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
        CALL TIMER_START('SHAP_FILT           [FORWARD_STEP]',myThid)
        CALL SHAP_FILT_APPLY_TS( gT, gS, myTime, myIter, 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
        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   

C--     Step forward fields and calculate time tendency terms.
        IF ( momStepping ) THEN
        CALL TIMER_START('DYNAMICS            [FORWARD_STEP]',mythid)
        CALL DYNAMICS( myTime, myIter, myThid )
        CALL TIMER_STOP ('DYNAMICS            [FORWARD_STEP]',mythid)
        ENDIF

#ifdef ALLOW_NONHYDROSTATIC
C--   Step forward W field in N-H algorithm
        IF ( momStepping .AND. nonHydrostatic ) THEN
          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
        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
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_START('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)
        CALL SHAP_FILT_APPLY_UV( gUnm1,gVnm1, myTime,myIter,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,myIter,myThid )
        ENDIF
        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)
        CALL ZONAL_FILT_APPLY_UV( gUnm1, gVnm1, 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 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

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)

#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

#ifndef EXCLUDE_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 /* EXCLUDE_MONITOR */

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 WRITE_CHECKPOINT(
     &        .FALSE., myTime, myIter, myThid )
      CALL TIMER_STOP ('WRITE_CHECKPOINT    [FORWARD_STEP]',myThid)

      END
1	heimbach	1.36	C $Header: /u/gcmpack/MITgcm/model/src/forward_step.F,v 1.35 2002/10/07 16:24:45 jmc Exp $
2	adcroft	1.15	C $Name: $
3	adcroft	1.1
4			#include "CPP_OPTIONS.h"
5
6	cnh	1.22	CBOP
7			C !ROUTINE: FORWARD_STEP
8			C !INTERFACE:
9	adcroft	1.13	SUBROUTINE FORWARD_STEP( iloop, myTime, myIter, myThid )
10	heimbach	1.12
11	cnh	1.22	C !DESCRIPTION: \bv
12			C *==================================================================
13			C \| SUBROUTINE forward_step
14			C \| o Run the ocean model and, optionally, evaluate a cost function.
15			C *==================================================================
16			C \|
17			C \| THE_MAIN_LOOP is the toplevel routine for the Tangent Linear and
18			C \| Adjoint Model Compiler (TAMC). For this purpose the initialization
19			C \| of the model was split into two parts. Those parameters that do
20			C \| not depend on a specific model run are set in INITIALISE_FIXED,
21			C \| whereas those that do depend on the specific realization are
22			C \| initialized in INITIALISE_VARIA.
23			C \|
24			C *==================================================================
25			C \ev
26	adcroft	1.1
27	cnh	1.22	C !USES:
28			IMPLICIT NONE
29			C == Global variables ==
30	adcroft	1.1	#include "SIZE.h"
31			#include "EEPARAMS.h"
32			#include "PARAMS.h"
33			#include "DYNVARS.h"
34	heimbach	1.12	#include "FFIELDS.h"
35
36	adcroft	1.1	#ifdef ALLOW_NONHYDROSTATIC
37			#include "CG3D.h"
38			#endif
39
40	jmc	1.27	#ifdef ALLOW_SHAP_FILT
41			#include "SHAP_FILT.h"
42			#endif
43			#ifdef ALLOW_ZONAL_FILT
44			#include "ZONAL_FILT.h"
45			#endif
46
47	heimbach	1.12	#ifdef ALLOW_AUTODIFF_TAMC
48	heimbach	1.30	# include "tamc.h"
49			# include "ctrl.h"
50			# include "ctrl_dummy.h"
51			# include "cost.h"
52			# ifdef INCLUDE_EXTERNAL_FORCING_PACKAGE
53			# include "exf_fields.h"
54			# ifdef ALLOW_BULKFORMULAE
55			# include "exf_constants.h"
56			# endif
57			# endif
58			# ifdef ALLOW_OBCS
59			# include "OBCS.h"
60			# endif
61	heimbach	1.12	#endif
62
63	cnh	1.22	C !LOCAL VARIABLES:
64			C == Routine arguments ==
65	adcroft	1.13	C note: under the multi-threaded model myiter and
66			C mytime are local variables passed around as routine
67			C arguments. Although this is fiddly it saves the need to
68			C impose additional synchronisation points when they are
69			C updated.
70			C myiter - iteration counter for this thread
71			C mytime - time counter for this thread
72			C mythid - thread number for this instance of the routine.
73	heimbach	1.12	integer iloop
74			integer mythid
75			integer myiter
76			_RL mytime
77	jmc	1.21	INTEGER bi,bj
78	heimbach	1.12
79	cnh	1.22	CEOP
80	heimbach	1.12
81
82			#ifdef ALLOW_AUTODIFF_TAMC
83	heimbach	1.14	C-- Reset the model iteration counter and the model time.
84	heimbach	1.12	myiter = nIter0 + (iloop-1)
85			mytime = startTime + float(iloop-1)*deltaTclock
86			#endif
87
88	heimbach	1.32	#if (defined (ALLOW_AUTODIFF_TAMC) && defined (ALLOW_AUTODIFF_MONITOR))
89	heimbach	1.16	C Include call to a dummy routine. Its adjoint will be
90			C called at the proper place in the adjoint code.
91			C The adjoint routine will print out adjoint values
92			C if requested. The location of the call is important,
93			C it has to be after the adjoint of the exchanges
94			C (DO_GTERM_BLOCKING_EXCHANGES).
95			CALL DUMMY_IN_STEPPING( myTime, myIter, myThid )
96	heimbach	1.26	CALL DO_FIELDS_BLOCKING_EXCHANGES( myThid )
97	heimbach	1.16	#endif
98
99	jmc	1.21	#ifdef EXACT_CONSERV
100			IF (exactConserv) THEN
101			C-- Update etaH(n+1) :
102	heimbach	1.36	CALL TIMER_START('UPDATE_ETAH [FORWARD_STEP]',mythid)
103	jmc	1.35	CALL UPDATE_ETAH( myTime, myIter, myThid )
104	heimbach	1.36	CALL TIMER_STOP ('UPDATE_ETAH [FORWARD_STEP]',mythid)
105	jmc	1.21	ENDIF
106			#endif /* EXACT_CONSERV */
107
108	jmc	1.18	#ifdef NONLIN_FRSURF
109			C-- compute the future surface level thickness
110	jmc	1.21	C according to etaH(n+1)
111	jmc	1.18	IF ( nonlinFreeSurf.GT.0) THEN
112	heimbach	1.36	CALL TIMER_START('CALC_SURF_DR [FORWARD_STEP]',mythid)
113	jmc	1.21	CALL CALC_SURF_DR(etaH, myTime, myIter, myThid )
114	heimbach	1.36	CALL TIMER_STOP ('CALC_SURF_DR [FORWARD_STEP]',mythid)
115	jmc	1.18	ENDIF
116	jmc	1.21	#endif /* NONLIN_FRSURF */
117	jmc	1.18
118	adcroft	1.13	C-- Load forcing/external data fields.
119	heimbach	1.28	#ifdef ALLOW_AUTODIFF_TAMC
120			c**************************************
121			#include "checkpoint_lev1_directives.h"
122			c**************************************
123	heimbach	1.23	#endif
124	heimbach	1.36	#ifdef INCLUDE_EXTERNAL_FORCING_PACKAGE
125			C NOTE, that although the exf package is part of the
126			C distribution, it is not currently maintained, i.e.
127			C exf is disabled by default in genmake.
128			IF ( .not. useSEAICE ) THEN
129			CALL TIMER_START('EXF_GETFORCING [FORWARD_STEP]',mythid)
130			CALL EXF_GETFORCING( mytime, myiter, mythid )
131			CALL TIMER_STOP ('EXF_GETFORCING [FORWARD_STEP]',mythid)
132			ENDIF
133	heimbach	1.12	#else
134	heimbach	1.36	IF ( .not. useSEAICE ) THEN
135			CALL TIMER_START('EXTERNAL_FIELDS_LOAD[FORWARD_STEP]',mythid)
136			CALL EXTERNAL_FIELDS_LOAD( mytime, myiter, mythid )
137			CALL TIMER_STOP ('EXTERNAL_FIELDS_LOAD[FORWARD_STEP]',mythid)
138			ENDIF
139			#endif /* INCLUDE_EXTERNAL_FORCING_PACKAGE */
140
141			#ifdef ALLOW_SEAICE
142			C-- Call sea ice model to compute forcing/external data fields. In
143			C addition to computing prognostic sea-ice variables and diagnosing the
144			C forcing/external data fields that drive the ocean model, SEAICE_MODEL
145			C also sets theta to the freezing point under sea-ice. The implied
146			C surface heat flux is then stored in variable surfaceTendencyTice,
147			C which is needed by KPP package (kpp_calc.F and kpp_transport_t.F)
148			C to diagnose surface buoyancy fluxes and for the non-local transport
149			C term. Because this call precedes model thermodynamics, temperature
150			C under sea-ice may not be "exactly" at the freezing point by the time
151			C theta is dumped or time-averaged.
152			IF ( useSEAICE ) THEN
153			CALL TIMER_START('SEAICE_MODEL [FORWARD_STEP]',myThid)
154			CALL SEAICE_MODEL( myTime, myIter, myThid )
155			CALL TIMER_STOP ('SEAICE_MODEL [FORWARD_STEP]',myThid)
156			ENDIF
157			#endif ALLOW_SEAICE
158	adcroft	1.15
159			C-- Step forward fields and calculate time tendency terms.
160	heimbach	1.36	CALL TIMER_START('THERMODYNAMICS [FORWARD_STEP]',mythid)
161	adcroft	1.15	CALL THERMODYNAMICS( myTime, myIter, myThid )
162	heimbach	1.36	CALL TIMER_STOP ('THERMODYNAMICS [FORWARD_STEP]',mythid)
163	jmc	1.35
164			C-- do exchanges (needed for DYNAMICS) when using stagger time-step :
165	heimbach	1.36	CALL TIMER_START('BLOCKING_EXCHANGES [FORWARD_STEP]',myThid)
166	jmc	1.35	CALL DO_STAGGER_FIELDS_EXCHANGES( myTime, myIter, myThid )
167	heimbach	1.36	CALL TIMER_STOP ('BLOCKING_EXCHANGES [FORWARD_STEP]',myThid)
168	jmc	1.24
169			#ifdef ALLOW_SHAP_FILT
170	jmc	1.27	IF (useSHAP_FILT .AND.
171			& staggerTimeStep .AND. shap_filt_TrStagg ) THEN
172	heimbach	1.36	CALL TIMER_START('SHAP_FILT [FORWARD_STEP]',myThid)
173	jmc	1.24	CALL SHAP_FILT_APPLY_TS( gT, gS, myTime, myIter, myThid )
174	heimbach	1.36	CALL TIMER_STOP ('SHAP_FILT [FORWARD_STEP]',myThid)
175	jmc	1.24	ENDIF
176			#endif
177	jmc	1.27	#ifdef ALLOW_ZONAL_FILT
178			IF (useZONAL_FILT .AND.
179			& staggerTimeStep .AND. zonal_filt_TrStagg ) THEN
180	heimbach	1.36	CALL TIMER_START('ZONAL_FILT_APPLY [FORWARD_STEP]',myThid)
181	jmc	1.27	CALL ZONAL_FILT_APPLY_TS( gT, gS, myThid )
182	heimbach	1.36	CALL TIMER_STOP ('ZONAL_FILT_APPLY [FORWARD_STEP]',myThid)
183	jmc	1.27	ENDIF
184			#endif
185	heimbach	1.12
186	adcroft	1.13	C-- Step forward fields and calculate time tendency terms.
187	adcroft	1.19	IF ( momStepping ) THEN
188	heimbach	1.36	CALL TIMER_START('DYNAMICS [FORWARD_STEP]',mythid)
189	heimbach	1.12	CALL DYNAMICS( myTime, myIter, myThid )
190	heimbach	1.36	CALL TIMER_STOP ('DYNAMICS [FORWARD_STEP]',mythid)
191	adcroft	1.19	ENDIF
192	heimbach	1.12
193	adcroft	1.1	#ifdef ALLOW_NONHYDROSTATIC
194			C-- Step forward W field in N-H algorithm
195	adcroft	1.19	IF ( momStepping .AND. nonHydrostatic ) THEN
196	heimbach	1.36	CALL TIMER_START('CALC_GW [FORWARD_STEP]',myThid)
197	heimbach	1.12	CALL CALC_GW(myThid)
198	heimbach	1.36	CALL TIMER_STOP ('CALC_GW [FORWARD_STEP]',myThid)
199	heimbach	1.12	ENDIF
200	adcroft	1.1	#endif
201	jmc	1.18
202			#ifdef NONLIN_FRSURF
203	jmc	1.21	C-- update hfacC,W,S and recip_hFac according to etaH(n+1) :
204	jmc	1.18	IF ( nonlinFreeSurf.GT.0) THEN
205	heimbach	1.36	CALL TIMER_START('UPDATE_SURF_DR [FORWARD_STEP]',mythid)
206	jmc	1.18	CALL UPDATE_SURF_DR( myTime, myIter, myThid )
207	heimbach	1.36	CALL TIMER_STOP ('UPDATE_SURF_DR [FORWARD_STEP]',myThid)
208	jmc	1.18	ENDIF
209			C- update also CG2D matrix (and preconditioner)
210	jmc	1.33	IF ( momStepping .AND. nonlinFreeSurf.GT.2 ) THEN
211	heimbach	1.36	CALL TIMER_START('UPDATE_CG2D [FORWARD_STEP]',mythid)
212	jmc	1.18	CALL UPDATE_CG2D( myTime, myIter, myThid )
213	heimbach	1.36	CALL TIMER_START('UPDATE_CG2D [FORWARD_STEP]',mythid)
214	adcroft	1.19	ENDIF
215	jmc	1.18	#endif
216	adcroft	1.1
217	jmc	1.27	C-- Apply Filters to u,v before SOLVE_FOR_PRESSURE
218			#ifdef ALLOW_SHAP_FILT
219			IF (useSHAP_FILT .AND. shap_filt_uvStar) THEN
220	heimbach	1.36	CALL TIMER_START('SHAP_FILT [FORWARD_STEP]',myThid)
221	jmc	1.27	CALL SHAP_FILT_APPLY_UV( gUnm1,gVnm1, myTime,myIter,myThid )
222			IF (implicDiv2Dflow.LT.1.) THEN
223			C-- Explicit+Implicit part of the Barotropic Flow Divergence
224			C => Filtering of uVel,vVel is necessary
225			CALL SHAP_FILT_APPLY_UV( uVel,vVel, myTime,myIter,myThid )
226			ENDIF
227	heimbach	1.36	CALL TIMER_STOP ('SHAP_FILT [FORWARD_STEP]',myThid)
228	jmc	1.27	ENDIF
229			#endif
230			#ifdef ALLOW_ZONAL_FILT
231			IF (useZONAL_FILT .AND. zonal_filt_uvStar) THEN
232	heimbach	1.36	CALL TIMER_START('ZONAL_FILT_APPLY [FORWARD_STEP]',myThid)
233	jmc	1.27	CALL ZONAL_FILT_APPLY_UV( gUnm1, gVnm1, myThid )
234			IF (implicDiv2Dflow.LT.1.) THEN
235			C-- Explicit+Implicit part of the Barotropic Flow Divergence
236			C => Filtering of uVel,vVel is necessary
237			CALL ZONAL_FILT_APPLY_UV( uVel, vVel, myThid )
238			ENDIF
239	heimbach	1.36	CALL TIMER_STOP ('ZONAL_FILT_APPLY [FORWARD_STEP]',myThid)
240	jmc	1.27	ENDIF
241			#endif
242	heimbach	1.12
243	adcroft	1.1	C-- Solve elliptic equation(s).
244			C Two-dimensional only for conventional hydrostatic or
245			C three-dimensional for non-hydrostatic and/or IGW scheme.
246	adcroft	1.19	IF ( momStepping ) THEN
247	heimbach	1.36	CALL TIMER_START('SOLVE_FOR_PRESSURE [FORWARD_STEP]',myThid)
248	jmc	1.31	CALL SOLVE_FOR_PRESSURE(myTime, myIter, myThid)
249	heimbach	1.36	CALL TIMER_STOP ('SOLVE_FOR_PRESSURE [FORWARD_STEP]',myThid)
250	adcroft	1.19	ENDIF
251	adcroft	1.1
252	adcroft	1.5	C-- Correct divergence in flow field and cycle time-stepping
253	jmc	1.7	C arrays (for all fields) ; update time-counter
254	heimbach	1.12	myIter = nIter0 + iLoop
255			myTime = startTime + deltaTClock * float(iLoop)
256	heimbach	1.36	CALL TIMER_START('THE_CORRECTION_STEP [FORWARD_STEP]',myThid)
257	heimbach	1.12	CALL THE_CORRECTION_STEP(myTime, myIter, myThid)
258	heimbach	1.36	CALL TIMER_STOP ('THE_CORRECTION_STEP [FORWARD_STEP]',myThid)
259	adcroft	1.5
260	adcroft	1.1	C-- Do "blocking" sends and receives for tendency "overlap" terms
261	heimbach	1.36	c CALL TIMER_START('BLOCKING_EXCHANGES [FORWARD_STEP]',myThid)
262	jmc	1.7	c CALL DO_GTERM_BLOCKING_EXCHANGES( myThid )
263	heimbach	1.36	c CALL TIMER_STOP ('BLOCKING_EXCHANGES [FORWARD_STEP]',myThid)
264	adcroft	1.5
265			C-- Do "blocking" sends and receives for field "overlap" terms
266	heimbach	1.36	CALL TIMER_START('BLOCKING_EXCHANGES [FORWARD_STEP]',myThid)
267	adcroft	1.5	CALL DO_FIELDS_BLOCKING_EXCHANGES( myThid )
268	heimbach	1.36	CALL TIMER_STOP ('BLOCKING_EXCHANGES [FORWARD_STEP]',myThid)
269	adcroft	1.20
270			#ifdef ALLOW_FLT
271			C-- Calculate float trajectories
272			IF (useFLT) THEN
273	heimbach	1.36	CALL TIMER_START('FLOATS [FORWARD_STEP]',myThid)
274	adcroft	1.20	CALL FLT_MAIN(myIter,myTime, myThid)
275	heimbach	1.36	CALL TIMER_STOP ('FLOATS [FORWARD_STEP]',myThid)
276	adcroft	1.20	ENDIF
277			#endif
278	heimbach	1.12
279			#ifndef EXCLUDE_MONITOR
280			C-- Check status of solution (statistics, cfl, etc...)
281	heimbach	1.36	CALL TIMER_START('MONITOR [FORWARD_STEP]',mythid)
282	heimbach	1.12	CALL MONITOR( myIter, myTime, myThid )
283	heimbach	1.36	CALL TIMER_STOP ('MONITOR [FORWARD_STEP]',myThid)
284	heimbach	1.12	#endif /* EXCLUDE_MONITOR */
285	adcroft	1.1
286	jmc	1.7	C-- Do IO if needed.
287	heimbach	1.36	CALL TIMER_START('DO_THE_MODEL_IO [FORWARD_STEP]',myThid)
288	heimbach	1.12	CALL DO_THE_MODEL_IO( myTime, myIter, myThid )
289	heimbach	1.36	CALL TIMER_STOP ('DO_THE_MODEL_IO [FORWARD_STEP]',myThid)
290	adcroft	1.1
291			C-- Save state for restarts
292	jmc	1.7	C Note: (jmc: is it still the case after ckp35 ?)
293	adcroft	1.1	C =====
294			C Because of the ordering of the timestepping code and
295			C tendency term code at end of loop model arrays hold
296			C U,V,T,S at "time-level" N but gu, gv, gs, gt, guNM1,...
297			C at "time-level" N+1/2 (guNM1 at "time-level" N+1/2 is
298	jmc	1.10	C gu at "time-level" N-1/2) and etaN at "time-level" N+1/2.
299	adcroft	1.1	C where N = I+timeLevBase-1
300			C Thus a checkpoint contains U.0000000000, GU.0000000001 and
301	jmc	1.10	C etaN.0000000001 in the indexing scheme used for the model
302	adcroft	1.1	C "state" files. This example is referred to as a checkpoint
303			C at time level 1
304	heimbach	1.36	CALL TIMER_START('WRITE_CHECKPOINT [FORWARD_STEP]',myThid)
305	adcroft	1.1	CALL WRITE_CHECKPOINT(
306	heimbach	1.12	& .FALSE., myTime, myIter, myThid )
307	heimbach	1.36	CALL TIMER_STOP ('WRITE_CHECKPOINT [FORWARD_STEP]',myThid)
308	adcroft	1.1
309			END