/[MITgcm]/MITgcm/model/src/adams_bashforth2.F
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Annotation of /MITgcm/model/src/adams_bashforth2.F

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Revision 1.1 - (hide annotations) (download)
Wed Sep 19 02:43:27 2001 UTC (22 years, 8 months ago) by adcroft
Branch: MAIN
CVS Tags: checkpoint40 
Re-arranged sequence of operations for Adams-Bashforth
 o this does not change numbers
 o this makes it very easy to extract forcing/diffusion out of ABII
   by changing calling sequence in calc_gt, calc_gs,...

Key modifications:
 o new s/r: ADAMS_BASHFORTH2  gT=3/2*gT-1/2*gTnm1
 o changed TIMESTEP_TRACER from gTnm1=t+dt*(3/2*gT-1/2*gTnm1)
   to  gT=T+dt*gT
 o changed CALC_GT,CALC_GS & CALC_GTR1 to calcuate "gT" defined
   by new timestep_tracer (ie. including forcing, ABII, N-L F-S, etc...)
   now calls ADAMS_BASHFORTH2 and FREESURF_RESCALE_G
 o changed CYCLE_TRACER appropriately  T=gT only

Other associated mods:
 o new s/r: FREESURF_RESCALE_G applies non-linear free-surface term
   this used to be in TIMESTEP_TRACER
 o added myIter as argument to CALC_GS,CALC_GT,CALC_GTR1
1 adcroft 1.1 C $Header: $
2     C $Name: $
3    
4     #include "CPP_OPTIONS.h"
5    
6     SUBROUTINE ADAMS_BASHFORTH2(
7     I bi, bj, K,
8     U gTracer, gTrNm1,
9     I myIter, myThid )
10     C /==========================================================\
11     C | S/R ADAMS_BASHFORTH2 |
12     C | o Extrapolate tendancies forward in time using |
13     C | quasi-second order Adams-Bashforth method. |
14     C \==========================================================/
15     IMPLICIT NONE
16    
17     C == Global variables ===
18     #include "SIZE.h"
19     #include "EEPARAMS.h"
20     #include "PARAMS.h"
21     #include "GAD.h"
22     #include "GRID.h"
23     #include "SURFACE.h"
24    
25     C == Routine Arguments ==
26     INTEGER bi,bj,K
27     _RL gTracer(1-OLx:sNx+OLx,1-OLy:sNy+OLy,Nr,nSx,nSy)
28     _RL gTrNm1 (1-OLx:sNx+OLx,1-OLy:sNy+OLy,Nr,nSx,nSy)
29     INTEGER myIter, myThid
30     C == Local variables ==
31     INTEGER i,j
32     _RL ab15,ab05
33     _RL gTrtmp
34    
35     C Adams-Bashforth timestepping weights
36     IF (myIter .EQ. 0) THEN
37     ab15=1.0
38     ab05=0.0
39     ELSE
40     ab15=1.5+abEps
41     ab05=-(0.5+abEps)
42     ENDIF
43    
44     C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----|
45    
46     C- Compute effective G-term with Adams-Bashforth weights:
47     DO j=1-Oly,sNy+Oly
48     DO i=1-Olx,sNx+Olx
49     gTrtmp = ab15*gTracer(i,j,k,bi,bj)
50     & + ab05*gTrNm1(i,j,k,bi,bj)
51     gTrNm1(i,j,k,bi,bj) = gTracer(i,j,k,bi,bj)
52     gTracer(i,j,k,bi,bj) = gTrtmp
53     ENDDO
54     ENDDO
55    
56     RETURN
57     END
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