pkg/generic_advdiff/gad_c4_adv_x.F

C $Header: /u/gcmpack/MITgcm/pkg/generic_advdiff/gad_c4_adv_x.F,v 1.4 2001/09/21 13:11:43 adcroft Exp $
C $Name:  $

#include "GAD_OPTIONS.h"

CBOP
C !ROUTINE: GAD_C4_ADV_X

C !INTERFACE: ==========================================================
      SUBROUTINE GAD_C4_ADV_X( 
     I           bi,bj,k,
     I           uTrans,
     I           tracer,
     O           uT,
     I           myThid )

C !DESCRIPTION:
C Calculates the area integrated zonal flux due to advection of a tracer
C using centered fourth-order interpolation:
C \begin{equation*}
C F^x_{adv} = U \overline{ \theta - \frac{1}{6} \delta_{ii} \theta }^i
C \end{equation*}
C Near boundaries, the scheme reduces to a second if the flow is away
C from the boundary and to third order if the flow is towards
C the boundary.

C !USES: ===============================================================
      IMPLICIT NONE
#include "SIZE.h"
#include "GRID.h"
#include "GAD.h"

C !INPUT PARAMETERS: ===================================================
C  bi,bj                :: tile indices
C  k                    :: vertical level
C  uTrans               :: zonal volume transport
C  tracer               :: tracer field
C  myThid               :: thread number
      INTEGER bi,bj,k
      _RL uTrans(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
      _RL tracer(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
      INTEGER myThid

C !OUTPUT PARAMETERS: ==================================================
C  uT                   :: zonal advective flux
      _RL uT    (1-OLx:sNx+OLx,1-OLy:sNy+OLy)

C !LOCAL VARIABLES: ====================================================
C  i,j                  :: loop indices
C  Rjm,Rj,Rjp           :: differences at i-1,i,i+1
C  Rjjm,Rjjp            :: second differences at i-1,i
      INTEGER i,j
      _RL Rjm,Rj,Rjp,Rjjm,Rjjp
CEOP

      DO j=1-Oly,sNy+Oly
       uT(1-Olx,j)=0.
       uT(2-Olx,j)=0.
       uT(sNx+Olx,j)=0.
       DO i=1-Olx+2,sNx+Olx-1
        Rjp=(tracer(i+1,j)-tracer(i,j))
     &     *maskW(i+1,j,k,bi,bj)
        Rj =(tracer(i,j)-tracer(i-1,j))
     &     *maskW(i,j,k,bi,bj)
        Rjm=(tracer(i-1,j)-tracer(i-2,j))
     &     *maskW(i-1,j,k,bi,bj)
        Rjjp=(Rjp-Rj)
        Rjjm=(Rj-Rjm)
        uT(i,j) =
     &   uTrans(i,j)*(
     &     Tracer(i,j)+Tracer(i-1,j)-oneSixth*( Rjjp+Rjjm )
     &               )*0.5 _d 0
     &  +ABS( uTrans(i,j) )*0.5 _d 0*oneSixth*( Rjjp-Rjjm )
     &    *( 1. _d 0 - maskW(i-1,j,k,bi,bj)*maskW(i+1,j,k,bi,bj) )
       ENDDO
      ENDDO

      RETURN
      END
1	C $Header: /u/gcmpack/MITgcm/pkg/generic_advdiff/gad_c4_adv_x.F,v 1.4 2001/09/21 13:11:43 adcroft Exp $
2	C $Name: $
3
4	#include "GAD_OPTIONS.h"
5
6	CBOP
7	C !ROUTINE: GAD_C4_ADV_X
8
9	C !INTERFACE: ==========================================================
10	SUBROUTINE GAD_C4_ADV_X(
11	I bi,bj,k,
12	I uTrans,
13	I tracer,
14	O uT,
15	I myThid )
16
17	C !DESCRIPTION:
18	C Calculates the area integrated zonal flux due to advection of a tracer
19	C using centered fourth-order interpolation:
20	C \begin{equation*}
21	C F^x_{adv} = U \overline{ \theta - \frac{1}{6} \delta_{ii} \theta }^i
22	C \end{equation*}
23	C Near boundaries, the scheme reduces to a second if the flow is away
24	C from the boundary and to third order if the flow is towards
25	C the boundary.
26
27	C !USES: ===============================================================
28	IMPLICIT NONE
29	#include "SIZE.h"
30	#include "GRID.h"
31	#include "GAD.h"
32
33	C !INPUT PARAMETERS: ===================================================
34	C bi,bj :: tile indices
35	C k :: vertical level
36	C uTrans :: zonal volume transport
37	C tracer :: tracer field
38	C myThid :: thread number
39	INTEGER bi,bj,k
40	_RL uTrans(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
41	_RL tracer(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
42	INTEGER myThid
43
44	C !OUTPUT PARAMETERS: ==================================================
45	C uT :: zonal advective flux
46	_RL uT (1-OLx:sNx+OLx,1-OLy:sNy+OLy)
47
48	C !LOCAL VARIABLES: ====================================================
49	C i,j :: loop indices
50	C Rjm,Rj,Rjp :: differences at i-1,i,i+1
51	C Rjjm,Rjjp :: second differences at i-1,i
52	INTEGER i,j
53	_RL Rjm,Rj,Rjp,Rjjm,Rjjp
54	CEOP
55
56	DO j=1-Oly,sNy+Oly
57	uT(1-Olx,j)=0.
58	uT(2-Olx,j)=0.
59	uT(sNx+Olx,j)=0.
60	DO i=1-Olx+2,sNx+Olx-1
61	Rjp=(tracer(i+1,j)-tracer(i,j))
62	& *maskW(i+1,j,k,bi,bj)
63	Rj =(tracer(i,j)-tracer(i-1,j))
64	& *maskW(i,j,k,bi,bj)
65	Rjm=(tracer(i-1,j)-tracer(i-2,j))
66	& *maskW(i-1,j,k,bi,bj)
67	Rjjp=(Rjp-Rj)
68	Rjjm=(Rj-Rjm)
69	uT(i,j) =
70	& uTrans(i,j)*(
71	& Tracer(i,j)+Tracer(i-1,j)-oneSixth*( Rjjp+Rjjm )
72	& )*0.5 _d 0
73	& +ABS( uTrans(i,j) )0.5 _d 0oneSixth*( Rjjp-Rjjm )
74	& ( 1. _d 0 - maskW(i-1,j,k,bi,bj)maskW(i+1,j,k,bi,bj) )
75	ENDDO
76	ENDDO
77
78	RETURN
79	END