C $Header: /u/gcmpack/MITgcm/pkg/seaice/seaice_ocean_stress.F,v 1.9 2006/06/14 16:08:36 mlosch Exp $
C $Name: $
#include "SEAICE_OPTIONS.h"
CStartOfInterface
SUBROUTINE SEAICE_OCEAN_STRESS(
I myTime, myIter, myThid )
C /==========================================================\
C | SUBROUTINE SEAICE_OCEAN_STRESS |
C | o Calculate ocean surface stresses |
C | - C-grid version |
C |==========================================================|
C \==========================================================/
IMPLICIT NONE
C === Global variables ===
#include "SIZE.h"
#include "EEPARAMS.h"
#include "PARAMS.h"
#include "GRID.h"
#include "FFIELDS.h"
#include "SEAICE.h"
#include "SEAICE_PARAMS.h"
#include "SEAICE_FFIELDS.h"
C === Routine arguments ===
C myTime - Simulation time
C myIter - Simulation timestep number
C myThid - Thread no. that called this routine.
_RL myTime
INTEGER myIter
INTEGER myThid
CEndOfInterface
#ifdef SEAICE_CGRID
C === Local variables ===
C i,j,bi,bj - Loop counters
INTEGER i, j, bi, bj
_RL SINWAT, COSWAT, SINWIN, COSWIN
_RL fuIce, fvIce, FX, FY
_RL areaW, areaS
_RL press (1-Olx:sNx+Olx,1-Oly:sNy+Oly,nSx,nSy)
_RL etaPlusZeta (1-Olx:sNx+Olx,1-Oly:sNy+Oly)
_RL zetaMinusEta(1-Olx:sNx+Olx,1-Oly:sNy+Oly)
_RL etaMeanZ (1-Olx:sNx+Olx,1-Oly:sNy+Oly)
_RL etaMeanU (1-Olx:sNx+Olx,1-Oly:sNy+Oly)
_RL etaMeanV (1-Olx:sNx+Olx,1-Oly:sNy+Oly)
_RL dVdx (1-Olx:sNx+Olx,1-Oly:sNy+Oly)
_RL dVdy (1-Olx:sNx+Olx,1-Oly:sNy+Oly)
_RL dUdx (1-Olx:sNx+Olx,1-Oly:sNy+Oly)
_RL dUdy (1-Olx:sNx+Olx,1-Oly:sNy+Oly)
c introduce turning angle (default is zero)
SINWAT=SIN(SEAICE_waterTurnAngle*deg2rad)
COSWAT=COS(SEAICE_waterTurnAngle*deg2rad)
SINWIN=SIN(SEAICE_airTurnAngle*deg2rad)
COSWIN=COS(SEAICE_airTurnAngle*deg2rad)
C-- Update overlap regions
CALL EXCH_UV_XY_RL(WINDX, WINDY, .TRUE., myThid)
#ifndef SEAICE_EXTERNAL_FLUXES
C-- Interpolate wind stress (N/m^2) from C-points of C-grid
C to U and V points of C-grid for forcing the ocean model.
DO bj=myByLo(myThid),myByHi(myThid)
DO bi=myBxLo(myThid),myBxHi(myThid)
DO j=1,sNy
DO i=1,sNx
fu(I,J,bi,bj)=0.5*(WINDX(I,J,bi,bj) + WINDX(I-1,J,bi,bj))
fv(I,J,bi,bj)=0.5*(WINDY(I,J,bi,bj) + WINDY(I,J-1,bi,bj))
ENDDO
ENDDO
ENDDO
ENDDO
#endif /* ifndef SEAICE_EXTERNAL_FLUXES */
IF ( useHB87StressCoupling ) THEN
C
C use an intergral over ice and ocean surface layer to define
C surface stresses on ocean following Hibler and Bryan (1987, JPO)
C
C recompute viscosities from updated ice velocities
CALL SEAICE_CALC_VISCOSITIES(
I uIce(1-Olx,1-Oly,1,1,1), vIce(1-Olx,1-Oly,1,1,1),
I zMin, zMax, hEffM, press0,
O eta, zeta, press,
#ifdef SEAICE_ALLOW_EVP
O seaice_div, seaice_tension, seaice_shear,
#endif /* SEAICE_ALLOW_EVP */
I myThid )
C re-compute internal stresses with updated ice velocities
DO bj=myByLo(myThid),myByHi(myThid)
DO bi=myBxLo(myThid),myBxHi(myThid)
DO j=1-Oly+1,sNy+Oly-1
DO i=1-Olx+1,sNx+Olx-1
etaPlusZeta (I,J) = eta(I,J,bi,bj) + zeta(I,J,bi,bj)
zetaMinusEta(I,J) = zeta(I,J,bi,bj) - eta(I,J,bi,bj)
etaMeanU (I,J) =
& HALF*(ETA (I,J,bi,bj) + ETA (I-1,J ,bi,bj))
etaMeanV (I,J) =
& HALF*(ETA (I,J,bi,bj) + ETA (I ,J-1,bi,bj))
etaMeanZ (I,J) = QUART *
& ( eta(I ,J,bi,bj) + eta(I ,J-1,bi,bj)
& + eta(I-1,J,bi,bj) + eta(I-1,J-1,bi,bj) )
dUdx(I,J) = ( uIce(I+1,J,1,bi,bj) - uIce(I,J,1,bi,bj) )
& * _recip_dxF(I,J,bi,bj)
dUdy(I,J) = ( uIce(I,J+1,1,bi,bj) - uIce(I,J,1,bi,bj) )
& * _recip_dyU(I,J+1,bi,bj)
dVdx(I,J) = ( vIce(I+1,J,1,bi,bj) - vIce(I,J,1,bi,bj) )
& * _recip_dxV(I+1,J,bi,bj)
dVdy(I,J) = ( vIce(I,J+1,1,bi,bj) - vIce(I,J,1,bi,bj) )
& * _recip_dyF(I,J,bi,bj)
ENDDO
ENDDO
DO J = 1,sNy
DO I = 1,sNx
C First FX = (d/dx)*sigma
C + d/dx[ eta+zeta d/dx ] U
FX = _recip_dxC(I,J,bi,bj) *
& ( etaPlusZeta(I ,J) * dUdx(I ,J)
& - etaPlusZeta(I-1,J) * dUdx(I-1,J) )
C + (d/dy)[eta*(d/dy + tanphi/a)] U (also on UVRT1/2)
FX = FX + _recip_dyG(I,J,bi,bj) * (
& ( etaMeanZ(I,J+1) * dUdy(I,J+1)
& - etaMeanZ(I,J ) * dUdy(I,J )
& )
& - ( etaMeanZ(I,J+1)
& * ( uIce(I,J+1,1,bi,bj)+uIce(I,J,1,bi,bj) )
& - etaMeanZ(I,J )
& * ( uIce(I,J-1,1,bi,bj)+uIce(I,J,1,bi,bj) ) )
& * 0.5 _d 0 * _tanPhiAtU(I,J,bi,bj)
& * recip_rSphere )
C - 2*eta*(tanphi/a) * ( tanphi/a ) U
FX = FX - TWO * uIce(I,J,1,bi,bj)
& * etaMeanU(I,J)*recip_rSphere*recip_rSphere
& * _tanPhiAtU(I,J,bi,bj) * _tanPhiAtU(I,J,bi,bj)
C + d/dx[ (zeta-eta) dV/dy]
FX = FX +
& ( zetaMinusEta(I ,J ) * dVdy(I ,J )
& - zetaMinusEta(I-1,J ) * dVdy(I-1,J )
& ) * _recip_dxC(I,J,bi,bj)
C + d/dy[ eta dV/x ]
FX = FX + (
& etaMeanZ(I,J+1)
& * ( vIce(I ,J+1,1,bi,bj) - vIce(I-1,J+1,1,bi,bj) )
& * _recip_dxV(I,J+1,bi,bj)
& - etaMeanZ(I,J )
& * ( vIce(I ,J,1,bi,bj) - vIce(I-1,J,1,bi,bj) )
& * _recip_dxV(I,J,bi,bj)
& ) * _recip_dyG(I,J,bi,bj)
C - d/dx[ (eta+zeta) * v * (tanphi/a) ]
FX = FX - (
& etaPlusZeta(I ,J)
& * 0.5 * (vIce(I ,J,1,bi,bj)+vIce(I ,J+1,1,bi,bj))
& * 0.5 * ( _tanPhiAtU(I ,J,bi,bj)
& + _tanPhiAtU(I+1,J,bi,bj) )
& - etaPlusZeta(I-1,J) *
& * 0.5 * (vIce(I-1,J,1,bi,bj)+vIce(I-1,J+1,1,bi,bj))
& * 0.5 * ( _tanPhiAtU(I-1,J,bi,bj)
& + _tanPhiAtU(I ,J,bi,bj) )
& )* _recip_dxC(I,J,bi,bj)*recip_rSphere
C - 2*eta*(tanphi/a) * dV/dx
FX = FX
& -TWO * etaMeanU(I,J) * _tanPhiAtV(I,J,bi,bj)
& *recip_rSphere
& *(vIce(I ,J,1,bi,bj) + vIce(I ,J+1,1,bi,bj)
& - vIce(I-1,J,1,bi,bj) - vIce(I-1,J+1,1,bi,bj))
& * _recip_dxC(I,J,bi,bj)
C - (d/dx) P/2
FX = _maskW(I,J,1,bi,bj) * ( FX - _recip_dxC(I,J,bi,bj)
& * ( press(I,J,bi,bj) - press(I-1,J,bi,bj) ) )
C
C then FY = (d/dy)*sigma
C + d/dy [(eta+zeta) d/dy] V
FY = _recip_dyC(I,J,bi,bj) *
& ( dVdy(I,J ) * etaPlusZeta(I,J )
& - dVdy(I,J-1) * etaPlusZeta(I,J-1) )
C + d/dx [eta d/dx] V
FY = FY + _recip_dxC(I,J,bi,bj) *
& ( eta(I ,J,bi,bj) * dVdx(I ,J)
& - eta(I-1,J,bi,bj) * dVdx(I-1,J) )
C - d/dy [(zeta-eta) tanphi/a] V
FY = FY - _recip_dyC(I,J,bi,bj) * recip_rSphere * (
& zetaMinusEta(I,J ) * tanPhiAtU(I,J ,bi,bj)
& * 0.5 * ( vIce(I,J,1,bi,bj) + vIce(I,J+1,1,bi,bj))
& - zetaMinusEta(I,J-1) * tanPhiAtU(I,J-1,bi,bj)
& * 0.5 * ( vIce(I,J,1,bi,bj) + vIce(I,J-1,1,bi,bj)) )
C 2*eta tanphi/a ( - tanphi/a - d/dy) V
FY = FY - TWO*etaMeanV(I,J) * recip_rSphere
& * _tanPhiAtV(I,J,bi,bj) * (
& _tanPhiAtV(I,J,bi,bj) * recip_rSphere
& + _recip_dyC(I,J,bi,bj) *
& ( 0.5 * ( vIce(I,J,1,bi,bj) + vIce(I,J+1,1,bi,bj))
& - 0.5 * ( vIce(I,J,1,bi,bj) + vIce(I,J-1,1,bi,bj)) ) )
C + d/dy[ (zeta-eta) dU/dx ]
FY = FY +
& ( zetaMinusEta(I,J )*dUdx(I,J )
& - zetaMinusEta(I,J-1)*dUdx(I,J-1) )
& * _recip_dyC(I,J,bi,bj)
C + d/dx[ eta dU/dy ]
FY = FY + _recip_dxG(I,J,bi,bj) *
& ( etaMeanZ(I+1,J) * dUdy(I+1,J)
& - etaMeanZ(I ,J) * dUdy(I ,J) )
C + d/dx[ eta * (tanphi/a) * U ]
FY = FY + (
& etaMeanZ(I+1,J) * 0.5 *
& ( uIce(I+1,J ,1,bi,bj) * _tanPhiAtU(I+1,J ,bi,bj)
& + uIce(I+1,J-1,1,bi,bj) * _tanPhiAtU(I+1,J-1,bi,bj) )
& - etaMeanZ(I ,J) * 0.5 *
& ( uIce(I ,J ,1,bi,bj) * _tanPhiAtU(I ,J ,bi,bj)
& + uIce(I ,J-1,1,bi,bj) * _tanPhiAtU(I ,J ,bi,bj) )
& ) * _recip_dxG(I,J,bi,bj)*recip_rSphere
C + 2*eta*(tanphi/a) dU/dx
FY = FY +
& TWO * etaMeanV(I,J)*TWO * _tanPhiAtV(I,J,bi,bj)
& * ( uIce(I+1,J,1,bi,bj)+uIce(I+1,J-1,1,bi,bj)
& - uIce(I ,J,1,bi,bj)-uIce(I ,J-1,1,bi,bj) )
& * _recip_dxG(I,J,bi,bj) * recip_rSphere
C - (d/dy) P/2
FY = _maskS(I,J,1,bi,bj) * ( FY - _recip_dyC(I,J,bi,bj)
& * ( press(I,J,bi,bj) - press(I,J-1,bi,bj) ) )
C
C recompute wind stress over ice (done already in seaice_dynsolver,
C but not saved)
fuIce = 0.5 _d 0 *
& ( DAIRN(I ,J,bi,bj)*(
& COSWIN*uWind(I ,J,bi,bj)
& -SIGN(SINWIN, _fCori(I ,J,bi,bj))*vWind(I ,J,bi,bj) )
& + DAIRN(I-1,J,bi,bj)*(
& COSWIN*uWind(I-1,J,bi,bj)
& -SIGN(SINWIN, _fCori(I-1,J,bi,bj))*vWind(I-1,J,bi,bj) )
& )
fvIce = 0.5 _d 0 *
& ( DAIRN(I,J ,bi,bj)*(
& SIGN(SINWIN, _fCori(I ,J,bi,bj))*uWind(I,J ,bi,bj)
& +COSWIN*vWind(I,J ,bi,bj) )
& + DAIRN(I,J-1,bi,bj)*(
& SIGN(SINWIN, _fCori(I,J-1,bi,bj))*uWind(I,J-1,bi,bj)
& +COSWIN*vWind(I,J-1,bi,bj) )
& )
C average wind stress over ice and ocean and apply averaged wind
C stress and internal ice stresses to surface layer of ocean
areaW = 0.5 * (AREA(I,J,1,bi,bj) + AREA(I-1,J,1,bi,bj))
& * SEAICEstressFactor
areaS = 0.5 * (AREA(I,J,1,bi,bj) + AREA(I,J-1,1,bi,bj))
& * SEAICEstressFactor
fu(I,J,bi,bj)=(ONE-areaW)*fu(I,J,bi,bj)+areaW*fuIce
& + FX * SEAICEstressFactor
fv(I,J,bi,bj)=(ONE-areaS)*fv(I,J,bi,bj)+areaS*fvIce
& + FY * SEAICEstressFactor
END
DO
END
DO
ENDDO
ENDDO
ELSE
C-- Compute ice-affected wind stress (interpolate to U/V-points)
C by averaging wind stress and ice-ocean stress according to
C ice cover
DO bj=myByLo(myThid),myByHi(myThid)
DO bi=myBxLo(myThid),myBxHi(myThid)
DO j=1,sNy
DO i=1,sNx
fuIce=HALF*( DWATN(I,J,bi,bj)+DWATN(I,J+1,bi,bj) )*
& COSWAT *
& ( UICE(I,J,1,bi,bj)-GWATX(I,J,bi,bj) )
& - SIGN(SINWAT, _fCori(I,J,bi,bj)) * 0.5 _d 0 *
& ( DWATN(I ,J,bi,bj) *
& 0.5 _d 0*(vIce(I ,J ,1,bi,bj)-GWATY(I ,J ,bi,bj)
& +vIce(I ,J+1,1,bi,bj)-GWATY(I ,J+1,bi,bj))
& + DWATN(I-1,J,bi,bj) *
& 0.5 _d 0*(vIce(I-1,J ,1,bi,bj)-GWATY(I-1,J ,bi,bj)
& +vIce(I-1,J+1,1,bi,bj)-GWATY(I-1,J+1,bi,bj))
& )
fvIce=HALF*( DWATN(I,J,bi,bj)+DWATN(I+1,J,bi,bj) )*
& COSWAT *
& ( VICE(I,J,1,bi,bj)-GWATY(I,J,bi,bj) )
& + SIGN(SINWAT, _fCori(I,J,bi,bj)) * 0.5 _d 0 *
& ( DWATN(I,J ,bi,bj) *
& 0.5 _d 0*(uIce(I ,J ,1,bi,bj)-GWATX(I ,J ,bi,bj)
& +uIce(I+1,J ,1,bi,bj)-GWATX(I+1,J ,bi,bj))
& + DWATN(I,J-1,bi,bj) *
& 0.5 _d 0*(uIce(I ,J-1,1,bi,bj)-GWATX(I ,J-1,bi,bj)
& +uIce(I+1,J-1,1,bi,bj)-GWATX(I+1,J-1,bi,bj))
& )
areaW = 0.5 _d 0 * (AREA(I,J,1,bi,bj) + AREA(I-1,J,1,bi,bj))
& * SEAICEstressFactor
areaS = 0.5 _d 0 * (AREA(I,J,1,bi,bj) + AREA(I,J-1,1,bi,bj))
& * SEAICEstressFactor
fu(I,J,bi,bj)=(ONE-areaW)*fu(I,J,bi,bj)+areaW*fuIce
fv(I,J,bi,bj)=(ONE-areaS)*fv(I,J,bi,bj)+areaS*fvIce
ENDDO
ENDDO
ENDDO
ENDDO
ENDIF
CALL EXCH_UV_XY_RS(fu, fv, .TRUE., myThid)
#endif /* not SEAICE_CGRID */
RETURN
END