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MODULE obs_readmdt
!!======================================================================
!! *** MODULE obs_readmdt ***
!! Observation diagnostics: Read the MDT for SLA data (skeleton for now)
!!======================================================================
!! History : ! 2007-03 (K. Mogensen) Initial skeleton version
!! ! 2007-04 (E. Remy) migration and improvement from OPAVAR
!!----------------------------------------------------------------------
!!----------------------------------------------------------------------
!! obs_rea_mdt : Driver for reading MDT
!! obs_offset_mdt : Remove the offset between the model MDT and the used one
!!----------------------------------------------------------------------
USE par_kind ! Precision variables
USE par_oce ! Domain parameters
USE in_out_manager ! I/O manager
USE obs_surf_def ! Surface observation definitions
USE obs_inter_sup ! Interpolation support routines
USE obs_inter_h2d ! 2D interpolation
USE obs_utils ! Various observation tools
USE iom_nf90 ! IOM NetCDF
USE netcdf ! NetCDF library
USE lib_mpp ! MPP library
USE dom_oce, ONLY : & ! Domain variables
& tmask, tmask_i, e1e2t, gphit, glamt
USE obs_const, ONLY : obfillflt ! Fillvalue
USE oce , ONLY : ssh ! Model variables
IMPLICIT NONE
PRIVATE
PUBLIC obs_rea_mdt ! called by dia_obs_init
PUBLIC obs_offset_mdt ! called by obs_rea_mdt
INTEGER , PUBLIC :: nn_msshc = 1 ! MDT correction scheme
REAL(wp), PUBLIC :: rn_mdtcorr = 1.61_wp ! User specified MDT correction
REAL(wp), PUBLIC :: rn_mdtcutoff = 65.0_wp ! MDT cutoff for computed correction
!! * Substitutions
# include "do_loop_substitute.h90"
!!----------------------------------------------------------------------
!! NEMO/OCE 4.0 , NEMO Consortium (2018)
!! $Id: obs_readmdt.F90 13295 2020-07-10 18:24:21Z acc $
!! Software governed by the CeCILL license (see ./LICENSE)
!!----------------------------------------------------------------------
CONTAINS
SUBROUTINE obs_rea_mdt( sladata, k2dint, Kmm )
!!---------------------------------------------------------------------
!!
!! *** ROUTINE obs_rea_mdt ***
!!
!! ** Purpose : Read from file the MDT data (skeleton)
!!
!! ** Method :
!!
!! ** Action :
!!----------------------------------------------------------------------
USE iom
!
TYPE(obs_surf), INTENT(inout) :: sladata ! SLA data
INTEGER , INTENT(in) :: k2dint ! ?
INTEGER , INTENT(in) :: Kmm ! ?
!
CHARACTER(LEN=12), PARAMETER :: cpname = 'obs_rea_mdt'
CHARACTER(LEN=20), PARAMETER :: mdtname = 'slaReferenceLevel.nc'
INTEGER :: jobs ! Obs loop variable
INTEGER :: jpimdt, jpjmdt ! Number of grid point in lat/lon for the MDT
INTEGER :: iico, ijco ! Grid point indicies
INTEGER :: i_nx_id, i_ny_id, i_file_id, i_var_id, i_stat
INTEGER :: nummdt
!
REAL(wp), DIMENSION(1) :: zext, zobsmask
REAL(wp), DIMENSION(2,2,1) :: zweig
!
REAL(wp), DIMENSION(:,:,:), ALLOCATABLE :: zmask, zmdtl, zglam, zgphi
INTEGER , DIMENSION(:,:,:), ALLOCATABLE :: igrdi, igrdj
!
REAL(wp), DIMENSION(jpi,jpj) :: z_mdt, mdtmask
REAL(wp) :: zlam, zphi, zfill, zinfill ! local scalar
!!----------------------------------------------------------------------
IF(lwp)WRITE(numout,*)
IF(lwp)WRITE(numout,*) ' obs_rea_mdt : Read MDT for referencing altimeter anomalies'
IF(lwp)WRITE(numout,*) ' ------------- '
CALL FLUSH(numout)
CALL iom_open( mdtname, nummdt ) ! Open the file
! ! Get the MDT data
CALL iom_get ( nummdt, jpdom_global, 'sossheig', z_mdt(:,:) )
CALL iom_close(nummdt) ! Close the file
! Read in the fill value
zinfill = 0.0
i_stat = nf90_open( mdtname, nf90_nowrite, nummdt )
i_stat = nf90_inq_varid( nummdt, 'sossheig', i_var_id )
i_stat = nf90_get_att( nummdt, i_var_id, "_FillValue",zinfill)
zfill = zinfill
i_stat = nf90_close( nummdt )
! setup mask based on tmask and MDT mask
! set mask to 0 where the MDT is set to fillvalue
WHERE(z_mdt(:,:) /= zfill) ; mdtmask(:,:) = tmask(:,:,1)
ELSE WHERE ; mdtmask(:,:) = 0
END WHERE
! Remove the offset between the MDT used with the sla and the model MDT
IF( nn_msshc == 1 .OR. nn_msshc == 2 ) &
& CALL obs_offset_mdt( jpi, jpj, z_mdt, zfill, Kmm )
! Intepolate the MDT already on the model grid at the observation point
ALLOCATE( &
& igrdi(2,2,sladata%nsurf), &
& igrdj(2,2,sladata%nsurf), &
& zglam(2,2,sladata%nsurf), &
& zgphi(2,2,sladata%nsurf), &
& zmask(2,2,sladata%nsurf), &
& zmdtl(2,2,sladata%nsurf) &
& )
DO jobs = 1, sladata%nsurf
igrdi(1,1,jobs) = sladata%mi(jobs)-1
igrdj(1,1,jobs) = sladata%mj(jobs)-1
igrdi(1,2,jobs) = sladata%mi(jobs)-1
igrdj(1,2,jobs) = sladata%mj(jobs)
igrdi(2,1,jobs) = sladata%mi(jobs)
igrdj(2,1,jobs) = sladata%mj(jobs)-1
igrdi(2,2,jobs) = sladata%mi(jobs)
igrdj(2,2,jobs) = sladata%mj(jobs)
END DO
CALL obs_int_comm_2d( 2, 2, sladata%nsurf, jpi, jpj, igrdi, igrdj, glamt , zglam )
CALL obs_int_comm_2d( 2, 2, sladata%nsurf, jpi, jpj, igrdi, igrdj, gphit , zgphi )
CALL obs_int_comm_2d( 2, 2, sladata%nsurf, jpi, jpj, igrdi, igrdj, mdtmask, zmask )
CALL obs_int_comm_2d( 2, 2, sladata%nsurf, jpi, jpj, igrdi, igrdj, z_mdt , zmdtl )
DO jobs = 1, sladata%nsurf
zlam = sladata%rlam(jobs)
zphi = sladata%rphi(jobs)
CALL obs_int_h2d_init( 1, 1, k2dint, zlam, zphi, &
& zglam(:,:,jobs), zgphi(:,:,jobs), &
& zmask(:,:,jobs), zweig, zobsmask )
CALL obs_int_h2d( 1, 1, zweig, zmdtl(:,:,jobs), zext )
sladata%rext(jobs,2) = zext(1)
! mark any masked data with a QC flag
IF( zobsmask(1) == 0 ) sladata%nqc(jobs) = IBSET(sladata%nqc(jobs),15)
END DO
DEALLOCATE( &
& igrdi, &
& igrdj, &
& zglam, &
& zgphi, &
& zmask, &
& zmdtl &
& )
IF(lwp)WRITE(numout,*) ' ------------- '
!
END SUBROUTINE obs_rea_mdt
SUBROUTINE obs_offset_mdt( kpi, kpj, mdt, zfill, Kmm )
!!---------------------------------------------------------------------
!!
!! *** ROUTINE obs_offset_mdt ***
!!
!! ** Purpose : Compute a correction term for the MDT on the model grid
!! !!!!! IF it is on the model grid
!!
!! ** Method : Compute the mean difference between the model and the
!! used MDT and remove the offset.
!!
!! ** Action :
!!----------------------------------------------------------------------
INTEGER, INTENT(IN) :: kpi, kpj
INTEGER, INTENT(IN) :: Kmm
REAL(wp), DIMENSION(kpi,kpj), INTENT(INOUT) :: mdt ! MDT used on the model grid
REAL(wp) , INTENT(IN ) :: zfill
!
INTEGER :: ji, jj
REAL(wp) :: zdxdy, zarea, zeta1, zeta2, zcorr_mdt, zcorr_bcketa, zcorr ! local scalar
REAL(wp), DIMENSION(jpi,jpj) :: zpromsk
CHARACTER(LEN=14), PARAMETER :: cpname = 'obs_offset_mdt'
!!----------------------------------------------------------------------
! Initialize the local mask, for domain projection
! Also exclude mdt points which are set to missing data
DO ji = 1, jpi
DO jj = 1, jpj
zpromsk(ji,jj) = tmask_i(ji,jj)
IF ( ( gphit(ji,jj) .GT. rn_mdtcutoff ) &
&.OR.( gphit(ji,jj) .LT. -rn_mdtcutoff ) &
&.OR.( mdt(ji,jj) .EQ. zfill ) ) &
& zpromsk(ji,jj) = 0.0
END DO
END DO
! Compute MSSH mean over [0,360] x [-rn_mdtcutoff,rn_mdtcutoff]
zarea = 0.0
zeta1 = 0.0
zeta2 = 0.0
DO_2D( 1, 1, 1, 1 )
zdxdy = e1e2t(ji,jj) * zpromsk(ji,jj)
zarea = zarea + zdxdy
zeta1 = zeta1 + mdt(ji,jj) * zdxdy
zeta2 = zeta2 + ssh(ji,jj,Kmm) * zdxdy
END_2D
CALL mpp_sum( 'obs_readmdt', zeta1 )
CALL mpp_sum( 'obs_readmdt', zeta2 )
CALL mpp_sum( 'obs_readmdt', zarea )
zcorr_mdt = zeta1 / zarea
zcorr_bcketa = zeta2 / zarea
! Define correction term
zcorr = zcorr_mdt - zcorr_bcketa
! Correct spatial mean of the MSSH
IF( nn_msshc == 1 ) mdt(:,:) = mdt(:,:) - zcorr
! User defined value : 1.6 m for the Rio MDT compared to ORCA2 MDT
IF( nn_msshc == 2 ) mdt(:,:) = mdt(:,:) - rn_mdtcorr
IF(lwp) THEN
WRITE(numout,*)
WRITE(numout,*) ' obs_readmdt : rn_mdtcutoff = ', rn_mdtcutoff
WRITE(numout,*) ' ----------- zcorr_mdt = ', zcorr_mdt
WRITE(numout,*) ' zcorr_bcketa = ', zcorr_bcketa
WRITE(numout,*) ' zcorr = ', zcorr
WRITE(numout,*) ' nn_msshc = ', nn_msshc
ENDIF
IF ( nn_msshc == 0 ) WRITE(numout,*) ' MSSH correction is not applied'
IF ( nn_msshc == 1 ) WRITE(numout,*) ' MSSH correction is applied'
IF ( nn_msshc == 2 ) WRITE(numout,*) ' User defined MSSH correction'
!
END SUBROUTINE obs_offset_mdt
!!======================================================================
END MODULE obs_readmdt