model/src/adams_bashforth2.F

C $Header: /u/gcmpack/MITgcm/model/src/adams_bashforth2.F,v 1.6 2005/04/15 14:11:01 jmc Exp $
C $Name:  $

#include "CPP_OPTIONS.h"

CBOP
C     !ROUTINE: ADAMS_BASHFORTH2
C     !INTERFACE:
      SUBROUTINE ADAMS_BASHFORTH2(
     I                     bi, bj, k,
     U                     gTracer, gTrNm1,
     I                     startAB, myIter, myThid )
C     !DESCRIPTION: \bv
C     *==========================================================*
C     | S/R ADAMS_BASHFORTH2
C     | o Extrapolate tendencies forward in time using
C     |   quasi-second order Adams-Bashforth method.
C     *==========================================================*
C     \ev

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

C     !INPUT/OUTPUT PARAMETERS:
C     == Routine Arguments ==
C     bi,bj,k :: Tile and level indices
C     gTracer :: Tendency at current time  ( generally units of quantity/sec )
C     gTrNm1  :: Tendency at previous time ( generally units of quantity/sec )
C     startAB :: number of previous time level available to start/restart AB
C     myIter  :: Current time step number
C     myThid  :: Thread number of this thread
      INTEGER bi,bj,k
      _RL  gTracer(1-OLx:sNx+OLx,1-OLy:sNy+OLy,Nr,nSx,nSy)
      _RL  gTrNm1 (1-OLx:sNx+OLx,1-OLy:sNy+OLy,Nr,nSx,nSy)
      INTEGER startAB
      INTEGER myIter, myThid

C     !LOCAL VARIABLES:
C     == Local variables ==
C     i,j        :: Loop counters
C     ab15, ab05 :: Adams bashforth extrapolation weights.
      INTEGER i,j
      _RL ab15,ab05
      _RL gTrtmp
CEOP

C     Adams-Bashforth timestepping weights
      IF ( myIter.EQ.nIter0 .AND. startAB.EQ.0 ) THEN
       ab15 = 1. _d 0
       ab05 = 0. _d 0
      ELSE
       ab15 = 1.5 _d 0 + abEps
       ab05 = -( 0.5 _d 0 + abEps )
      ENDIF

C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----|

C-    Compute effective G-term with Adams-Bashforth weights:
      DO j=1-Oly,sNy+Oly
       DO i=1-Olx,sNx+Olx
        gTrtmp = ab15*gTracer(i,j,k,bi,bj)
     &         + ab05*gTrNm1(i,j,k,bi,bj)
        gTrNm1(i,j,k,bi,bj) = gTracer(i,j,k,bi,bj)
        gTracer(i,j,k,bi,bj) = gTrtmp
       ENDDO
      ENDDO

      RETURN
      END
1	jmc	1.7	C $Header: /u/gcmpack/MITgcm/model/src/adams_bashforth2.F,v 1.6 2005/04/15 14:11:01 jmc Exp $
2	cnh	1.2	C $Name: $
3	adcroft	1.1
4			#include "CPP_OPTIONS.h"
5
6	cnh	1.2	CBOP
7			C !ROUTINE: ADAMS_BASHFORTH2
8			C !INTERFACE:
9	adcroft	1.1	SUBROUTINE ADAMS_BASHFORTH2(
10	jmc	1.6	I bi, bj, k,
11	adcroft	1.1	U gTracer, gTrNm1,
12	jmc	1.7	I startAB, myIter, myThid )
13	cnh	1.2	C !DESCRIPTION: \bv
14			C ==========================================================
15	jmc	1.7	C \| S/R ADAMS_BASHFORTH2
16			C \| o Extrapolate tendencies forward in time using
17			C \| quasi-second order Adams-Bashforth method.
18	cnh	1.2	C ==========================================================
19			C \ev
20
21			C !USES:
22	adcroft	1.1	IMPLICIT NONE
23			C == Global variables ===
24			#include "SIZE.h"
25			#include "EEPARAMS.h"
26			#include "PARAMS.h"
27
28	cnh	1.2	C !INPUT/OUTPUT PARAMETERS:
29	adcroft	1.1	C == Routine Arguments ==
30	jmc	1.6	C bi,bj,k :: Tile and level indices
31	cnh	1.2	C gTracer :: Tendency at current time ( generally units of quantity/sec )
32			C gTrNm1 :: Tendency at previous time ( generally units of quantity/sec )
33	jmc	1.7	C startAB :: number of previous time level available to start/restart AB
34	cnh	1.2	C myIter :: Current time step number
35			C myThid :: Thread number of this thread
36	jmc	1.6	INTEGER bi,bj,k
37	adcroft	1.1	_RL gTracer(1-OLx:sNx+OLx,1-OLy:sNy+OLy,Nr,nSx,nSy)
38			_RL gTrNm1 (1-OLx:sNx+OLx,1-OLy:sNy+OLy,Nr,nSx,nSy)
39	jmc	1.7	INTEGER startAB
40	adcroft	1.1	INTEGER myIter, myThid
41	cnh	1.2
42			C !LOCAL VARIABLES:
43	adcroft	1.1	C == Local variables ==
44	cnh	1.2	C i,j :: Loop counters
45			C ab15, ab05 :: Adams bashforth extrapolation weights.
46	adcroft	1.1	INTEGER i,j
47			_RL ab15,ab05
48			_RL gTrtmp
49	cnh	1.2	CEOP
50	adcroft	1.1
51			C Adams-Bashforth timestepping weights
52	jmc	1.7	IF ( myIter.EQ.nIter0 .AND. startAB.EQ.0 ) THEN
53			ab15 = 1. _d 0
54			ab05 = 0. _d 0
55	adcroft	1.1	ELSE
56	jmc	1.7	ab15 = 1.5 _d 0 + abEps
57			ab05 = -( 0.5 _d 0 + abEps )
58	adcroft	1.1	ENDIF
59
60	jmc	1.7	C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-\|--+----\|
61	adcroft	1.1
62			C- Compute effective G-term with Adams-Bashforth weights:
63			DO j=1-Oly,sNy+Oly
64			DO i=1-Olx,sNx+Olx
65	jmc	1.7	gTrtmp = ab15*gTracer(i,j,k,bi,bj)
66	adcroft	1.1	& + ab05*gTrNm1(i,j,k,bi,bj)
67			gTrNm1(i,j,k,bi,bj) = gTracer(i,j,k,bi,bj)
68			gTracer(i,j,k,bi,bj) = gTrtmp
69			ENDDO
70			ENDDO
71
72			RETURN
73			END