/[MITgcm]/MITgcm/pkg/generic_advdiff/gad_dst2u1_adv_y.F
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Revision 1.6 - (hide annotations) (download)
Tue Dec 5 22:21:50 2006 UTC (17 years, 6 months ago) by jmc
Branch: MAIN
CVS Tags: mitgcm_mapl_00, checkpoint58u_post, checkpoint58w_post, checkpoint58x_post, checkpoint58t_post, checkpoint58v_post, checkpoint58s_post
Changes since 1.5: +3 -4 lines
change horizontal CFL for deep-model.

1 jmc 1.6 C $Header: /u/gcmpack/MITgcm/pkg/generic_advdiff/gad_dst2u1_adv_y.F,v 1.5 2006/06/19 14:40:43 jmc Exp $
2 jmc 1.1 C $Name: $
3    
4     #include "GAD_OPTIONS.h"
5    
6     CBOP
7     C !ROUTINE: GAD_DST2U1_ADV_Y
8    
9     C !INTERFACE: ==========================================================
10 jmc 1.3 SUBROUTINE GAD_DST2U1_ADV_Y(
11 jmc 1.1 I bi,bj,k, advectionScheme, deltaTloc,
12 jmc 1.4 I vTrans, vFld,
13 jmc 1.1 I tracer,
14     O vT,
15     I myThid )
16    
17     C !DESCRIPTION:
18     C Calculates the area integrated meridional flux due to advection
19 jmc 1.3 C of a tracer using second-order Direct Space and Time (DST-2)
20 jmc 1.1 C interpolation (=Lax-Wendroff) or simple 1rst order upwind scheme.
21    
22     C !USES: ===============================================================
23     IMPLICIT NONE
24     #include "SIZE.h"
25     #include "GRID.h"
26     #include "GAD.h"
27    
28     C !INPUT PARAMETERS: ===================================================
29     C bi,bj :: tile indices
30     C k :: vertical level
31     C advectionScheme :: advection scheme to use: either 2nd Order DST
32     C or 1rst Order Upwind
33     C vTrans :: meridional volume transport
34 jmc 1.4 C vFld :: meridional flow
35 jmc 1.1 C tracer :: tracer field
36     C myThid :: thread number
37     INTEGER bi,bj, k, advectionScheme
38     _RL deltaTloc
39     _RL vTrans(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
40 jmc 1.4 _RL vFld (1-OLx:sNx+OLx,1-OLy:sNy+OLy)
41 jmc 1.1 _RL tracer(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
42     INTEGER myThid
43    
44     C !OUTPUT PARAMETERS: ==================================================
45     C vT :: meridional advective flux
46     _RL vT (1-OLx:sNx+OLx,1-OLy:sNy+OLy)
47    
48     C !LOCAL VARIABLES: ====================================================
49     C i,j :: loop indices
50     C yLimit :: centered (vs upwind) fraction
51 jmc 1.4 C vLoc :: velocity [m/s], meridional component
52 jmc 1.1 C vCFL :: Courant-Friedrich-Levy number
53     INTEGER i,j
54 jmc 1.4 _RL vLoc, vCFL, yLimit, vAbs
55 jmc 1.1 CEOP
56    
57     yLimit = 0. _d 0
58     IF ( advectionScheme.EQ.ENUM_DST2 ) yLimit = 1. _d 0
59    
60     DO i=1-Olx,sNx+Olx
61     vT(i,1-Oly)=0.
62     ENDDO
63     DO j=1-Oly+1,sNy+Oly
64     DO i=1-Olx,sNx+Olx
65    
66 jmc 1.5 vLoc = vFld(i,j)
67 jmc 1.6 vCFL = ABS( vLoc*deltaTloc
68     & *recip_dyC(i,j,bi,bj)*recip_deepFacC(k) )
69 jmc 1.1
70 jmc 1.3 c vT(i,j) =
71     c & vTrans(i,j)*(tracer(i,j-1)+tracer(i,j))*0.5 _d 0
72     c & + ( 1. _d 0 - yLimit*(1. _d 0 - vCFL) )*ABS(vTrans(i,j))
73     c & *(tracer(i,j-1)-tracer(i,j))*0.5 _d 0
74     C-- above formulation produces large truncation error when:
75     C 1rst.O upWind and v > 0 & |tracer(i,j-1)| << |tracer(i,j)|
76     C or v < 0 & |tracer(i,j-1)| >> |tracer(i,j)|
77     C-- change to a more robust expression:
78     vAbs = ABS(vTrans(i,j))
79     & *( 1. _d 0 - yLimit*(1. _d 0 - vCFL) )
80     vT(i,j) = ( vTrans(i,j)+vAbs )* 0.5 _d 0 * tracer(i,j-1)
81     & + ( vTrans(i,j)-vAbs )* 0.5 _d 0 * tracer(i,j)
82    
83 jmc 1.1 ENDDO
84     ENDDO
85    
86     RETURN
87     END

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