/[MITgcm]/MITgcm/model/src/calc_gs.F
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Revision 1.2 - (hide annotations) (download)
Fri Apr 24 02:05:40 1998 UTC (26 years ago) by cnh
Branch: MAIN
CVS Tags: redigm, checkpoint1, checkpoint3, checkpoint2, kloop1, kloop2
Changes since 1.1: +1 -1 lines
Further $Id to $Header conversions

1 cnh 1.2 C $Header: calc_gs.F,v 1.1.1.1 1998/04/22 19:15:30 cnh Exp $
2 cnh 1.1
3     #include "CPP_EEOPTIONS.h"
4    
5     CStartOfInterFace
6     SUBROUTINE CALC_GS(
7     I bi,bj,iMin,iMax,jMin,jMax,k,kM1,kUp,kDown,
8     I xA,yA,uTrans,vTrans,wTrans,maskup,
9     U af,df,fZon,fMer, fVerS,
10     I myThid )
11     C /==========================================================\
12     C | SUBROUTINE CALC_GS |
13     C | o Calculate the salinity tendency terms. |
14     C |==========================================================|
15     C | A procedure called EXTERNAL_FORCING_S is called from |
16     C | here. These procedures can be used to add per problem |
17     C | fresh water flux source terms. |
18     C | Note: Although it is slightly counter-intuitive the |
19     C | EXTERNAL_FORCING routine is not the place to put |
20     C | file I/O. Instead files that are required to |
21     C | calculate the external source terms are generally |
22     C | read during the model main loop. This makes the |
23     C | logisitics of multi-processing simpler and also |
24     C | makes the adjoint generation simpler. It also |
25     C | allows for I/O to overlap computation where that |
26     C | is supported by hardware. |
27     C | Aside from the problem specific term the code here |
28     C | forms the tendency terms due to advection and mixing |
29     C | The baseline implementation here uses a centered |
30     C | difference form for the advection term and a tensorial |
31     C | divergence of a flux form for the diffusive term. The |
32     C | diffusive term is formulated so that isopycnal mixing and|
33     C | GM-style subgrid-scale terms can be incorporated b simply|
34     C | setting the diffusion tensor terms appropriately. |
35     C \==========================================================/
36     IMPLICIT NONE
37    
38     C == GLobal variables ==
39     #include "SIZE.h"
40     #include "DYNVARS.h"
41     #include "EEPARAMS.h"
42     #include "PARAMS.h"
43     #include "GRID.h"
44    
45     C == Routine arguments ==
46     C fZon - Work array for flux of temperature in the east-west
47     C direction at the west face of a cell.
48     C fMer - Work array for flux of temperature in the north-south
49     C direction at the south face of a cell.
50     C fVerS - Flux of salinity (S) in the vertical
51     C direction at the upper(U) and lower(D) faces of a cell.
52     C maskUp - Land mask used to denote base of the domain.
53     C xA - Tracer cell face area normal to X
54     C yA - Tracer cell face area normal to X
55     C uTrans - Zonal volume transport through cell face
56     C vTrans - Meridional volume transport through cell face
57     C wTrans - Vertical volume transport through cell face
58     C af - Advective flux component work array
59     C df - Diffusive flux component work array
60     C bi, bj, iMin, iMax, jMin, jMax - Range of points for which calculation
61     C results will be set.
62     C myThid - Instance number for this innvocation of CALC_GS
63     _RL fZon (1-OLx:sNx+OLx,1-OLy:sNy+OLy)
64     _RL fMer (1-OLx:sNx+OLx,1-OLy:sNy+OLy)
65     _RL fVerS (1-OLx:sNx+OLx,1-OLy:sNy+OLy,2)
66     _RS xA (1-OLx:sNx+OLx,1-OLy:sNy+OLy)
67     _RS yA (1-OLx:sNx+OLx,1-OLy:sNy+OLy)
68     _RL uTrans(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
69     _RL vTrans(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
70     _RL wTrans(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
71     _RS maskUp(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
72     _RL af (1-OLx:sNx+OLx,1-OLy:sNy+OLy)
73     _RL df (1-OLx:sNx+OLx,1-OLy:sNy+OLy)
74     INTEGER kUp,kDown,kM1
75     INTEGER bi,bj,iMin,iMax,jMin,jMax
76     INTEGER myThid
77     CEndOfInterface
78    
79     C == Local variables ==
80     C I, J, K - Loop counters
81     INTEGER i,j,k
82     INTEGER afFacS, dfFacS
83    
84     afFacS = 1. _d 0
85     dfFacS = 1. _d 0
86    
87     C---
88     C--- Calculate advective and diffusive fluxes between cells.
89     C---
90    
91     C-- Zonal flux (fZon is at west face of "salt" cell)
92     C Advective component of zonal flux
93     DO j=jMin,jMax
94     DO i=iMin,iMax
95     af(i,j) =
96     & uTrans(i,j)*(salt(i,j,k,bi,bj)+salt(i-1,j,k,bi,bj))*0.5 _d 0
97     ENDDO
98     ENDDO
99     C Diffusive component of zonal flux
100     DO j=jMin,jMax
101     DO i=iMin,iMax
102     df(i,j) =
103     & -diffKhS*xA(i,j)*rdxC(i,j,bi,bj)
104     & *(salt(i,j,k,bi,bj)-salt(i-1,j,k,bi,bj))
105     ENDDO
106     ENDDO
107     C Net zonal flux
108     DO j=jMin,jMax
109     DO i=iMin,iMax
110     fZon(i,j) = afFacS*af(i,j) + dfFacS*df(i,j)
111     ENDDO
112     ENDDO
113    
114     C-- Meridional flux (fMer is at south face of "salt" cell)
115     C Advective component of meridional flux
116     DO j=jMin,jMax
117     DO i=iMin,iMax
118     C Advective component of meridional flux
119     af(i,j) =
120     & vTrans(i,j)*(salt(i,j,k,bi,bj)+salt(i,j-1,k,bi,bj))*0.5 _d 0
121     ENDDO
122     ENDDO
123     C Diffusive component of meridional flux
124     DO j=jMin,jMax
125     DO i=iMin,iMax
126     df(i,j) =
127     & -diffKhS*yA(i,j)*rdyC(i,j,bi,bj)
128     & *(salt(i,j,k,bi,bj)-salt(i,j-1,k,bi,bj))
129     ENDDO
130     ENDDO
131     C Net meridional flux
132     DO j=jMin,jMax
133     DO i=iMin,iMax
134     fMer(i,j) = afFacS*af(i,j) + dfFacS*df(i,j)
135     ENDDO
136     ENDDO
137    
138     C-- Vertical flux (fVerS) above
139     C Note: For K=1 then KM1=1 this gives a dS/dz = 0 upper
140     C boundary condition.
141     C Advective component of vertical flux
142     DO j=jMin,jMax
143     DO i=iMin,iMax
144     af(i,j) =
145     & wTrans(i,j)*(salt(i,j,k,bi,bj)+salt(i,j,kM1,bi,bj))*0.5 _d 0
146     ENDDO
147     ENDDO
148     C Diffusive component of vertical flux
149     DO j=jMin,jMax
150     DO i=iMin,iMax
151     df(i,j) =
152     & -diffKzS*zA(i,j,bi,bj)*rdzC(k)
153     & *(salt(i,j,kM1,bi,bj)-salt(i,j,k,bi,bj))
154     ENDDO
155     ENDDO
156     C Net vertical flux
157     DO j=jMin,jMax
158     DO i=iMin,iMax
159     fVerS(i,j,kUp) = (afFacS*af(i,j) + dfFacS*df(i,j))*maskUp(i,j)
160     ENDDO
161     ENDDO
162    
163     C-- Tendency is minus divergence of the fluxes.
164     C Note. Tendency terms will only be correct for range
165     C i=iMin+1:iMax-1, j=jMin+1:jMax-1. Edge points
166     C will contain valid floating point numbers but
167     C they are not algorithmically correct. These points
168     C are not used.
169     DO j=jMin,jMax
170     DO i=iMin,iMax
171     gS(i,j,k,bi,bj)=
172     & -rHFacC(i,j,k,bi,bj)*rdzF(k)*rDxF(i,j,bi,bj)*rDyF(i,j,bi,bj)
173     & *(
174     & +( fZon(i+1,j)-fZon(i,j) )
175     & +( fMer(i,j+1)-fMer(i,j) )
176     & +( fVerS(i,j,kUp)-fVerS(i,j,kDown) )
177     & )
178     ENDDO
179     ENDDO
180    
181     C-- External haline forcing term(s)
182    
183     RETURN
184     END

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