/[MITgcm]/MITgcm/pkg/mom_vecinv/mom_calc_strain.F
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Contents of /MITgcm/pkg/mom_vecinv/mom_calc_strain.F

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Revision 1.2 - (show annotations) (download)
Tue Nov 27 15:39:15 2001 UTC (22 years, 5 months ago) by adcroft
Branch: MAIN
Changes since 1.1: +33 -14 lines
Updated comments (protex)

1 C $Header: /u/gcmpack/models/MITgcmUV/pkg/mom_vecinv/mom_calc_strain.F,v 1.1 2001/09/06 14:23:58 adcroft Exp $
2 C $Name: $
3
4 #include "CPP_OPTIONS.h"
5
6 CBOP
7 C !ROUTINE: MOM_CALC_STRAIN
8
9 C !INTERFACE: ==========================================================
10 SUBROUTINE MOM_CALC_STRAIN(
11 I bi,bj,k,
12 I uFld, vFld, hFacZ,
13 O strain,
14 I myThid)
15
16 C !DESCRIPTION:
17 C Calculates the strain of the horizontal flow field (at vorticity points):
18 C \begin{equation*}
19 C D_S = \frac{\Delta y_u}{\Delta x_v} \delta_i \frac{v}{\Delta y_c}
20 C \frac{\Delta x_v}{\Delta y_u} \delta_j \frac{u}{\Delta x_c}
21 C \end{equation*}
22 C assuming free-slip boundaries.
23
24 C !USES: ===============================================================
25 IMPLICIT NONE
26 #include "SIZE.h"
27 #include "EEPARAMS.h"
28 #include "PARAMS.h"
29 #include "GRID.h"
30
31 C !INPUT PARAMETERS: ===================================================
32 C bi,bj :: tile indices
33 C k :: vertical level
34 C uFld :: zonal flow
35 C vFld :: meridional flow
36 C hFacZ :: open-water thickness at vorticity points
37 C myThid :: thread number
38 INTEGER bi,bj,k
39 _RL uFld(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
40 _RL vFld(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
41 _RS hFacZ(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
42 INTEGER myThid
43
44 C !OUTPUT PARAMETERS: ==================================================
45 C strain :: strain of horizontal flow
46 _RL strain(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
47
48 C !LOCAL VARIABLES: ====================================================
49 C i,j :: loop indices
50 INTEGER i,j
51 CEOP
52
53 DO J=2-Oly,sNy+Oly
54 DO I=2-Olx,sNx+Olx
55
56 C Strain of horizontal flow field (ignoring lopping factors)
57 strain(I,J)=
58 & dyu(I,J,bi,bj)*recip_dxv(I,J,bi,bj)*(
59 & vFld( I , J )*recip_dyc( I , J ,bi,bj)
60 & -vFld(I-1, J )*recip_dyc(I-1, J ,bi,bj) )
61 & +dxv(I,J,bi,bj)*recip_dyu(I,J,bi,bj)*(
62 & +uFld( I , J )*recip_dxc( I , J ,bi,bj)
63 & -uFld( I ,J-1)*recip_dxc( I ,J-1,bi,bj) )
64
65 C Set strain to zero on boundaries (free-slip)
66 IF (hFacZ(i,j).EQ.0.) THEN
67 strain(I,J)=0.
68 ENDIF
69
70 ENDDO
71 ENDDO
72
73 C Special stuff for Cubed Sphere
74 IF (useCubedSphereExchange) THEN
75 I=1
76 J=1
77 strain(I,J)=0.
78 I=sNx+1
79 J=1
80 strain(I,J)=0.
81 I=1
82 J=sNy+1
83 strain(I,J)=0.
84 I=sNx+1
85 J=sNy+1
86 strain(I,J)=0.
87 ENDIF
88
89 RETURN
90 END

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