w3smcomd Module Reference

Service module for support of SMC regridding and interpolation. More...

Functions/Subroutines
subroutine	smc_interp ()
	Generate SMC interpolation/output information. More...
subroutine	w3s2xy_smcrg (S, XY)
	Regrid SMC data onto a regular grid. More...
subroutine	w3s2xy_smcrg_dir (S, XY)
	Regrid directional SMC data onto a regular grid. More...
subroutine	mapsta_smc ()
	Calculates a new MAPSTA using SMC grid cell averaging. More...
subroutine	read_smcint ()
	Read interpolation information from smcint.ww3. More...
subroutine	calc_interp ()
	Calculates weights for SMC to arbitrary grid intepolation. More...
subroutine	w3s2xy_smcnn (S, XY, DIRN)
	Fill regular grid using nearest SMC point data. More...
subroutine	w3s2xy_smcnn_int (S, XY, DIRN)
	Nearest neighbour interpolation. More...
subroutine	w3s2xy_smc (S, XY, DIR)
	Entry point for SMC version of W3S2XY. More...

Variables
double precision	sxo
	Output grid longitude origin. More...
double precision	syo
	Output grid latitude origin. More...
double precision	exo
	Output grid final longitude. More...
double precision	eyo
	Output grid final latitude. More...
double precision	dxo
	Output grid cell longitude size. More...
double precision	dyo
	Output grid cell latitude size. More...
integer	nxo
	Output grid number of longitude cells. More...
integer	nyo
	Output grid number of latitude cells. More...
integer	smcotype
	Type of SMC output: 1=seapoint grid of SMC cells; 2=regridding to regular grid; 3=interpolation to arbtrary grid; 4=nearest neighbour interpolation to arbitrary grid. More...
integer	celfac
	Output grid cell scaling factor; should be an integer power of 2. More...
integer, dimension(:), allocatable	xidx
	X-indices of SMC cells in regular grid. More...
integer, dimension(:), allocatable	yidx
	Y-Indices of SMC cells in regular grid. More...
integer, dimension(:), allocatable	xspan
	Number of longitude cells SMC cell spans. More...
integer, dimension(:), allocatable	yspan
	Number of longitude cells SMC cell spans. More...
real, dimension(:), allocatable	wts
	Regridding weights. More...
real, dimension(:,:), allocatable	cov
	Wet fraction (coverage) of cell. More...
integer, dimension(:,:), allocatable	mapsmc
	Regridded MAPSTA. More...
logical, dimension(:), allocatable	smcmask
	Mask for type 1 output (flat array) More...
integer, dimension(:), allocatable	smcidx
	Indices of SMC cells within output grid domain. More...
integer, dimension(:), allocatable	smccx
	SMC grid definition. More...
integer, dimension(:), allocatable	smccy
	Latitude cell size factors. More...
real	dlat
	Base longitude cell size. More...
real	dlon
	Base latitude cell size. More...
integer	cfac
	SMC scaling factor (number of levels) More...
real	noval
	Fill value for seapoints with no value. More...
integer, dimension(:,:), allocatable	nnidx
	Nearest neighbour SMC point to regular grid. More...
real, dimension(:,:), allocatable	xdist
	Lng. More...
real, dimension(:,:), allocatable	ydist
	Lat. More...
integer	ndsmc
	ww3_smcint file unit number More...
integer	smcnout
	Number of SMC output cells. More...
integer	nsmc
	Number of SMC cells used in regridding. More...

Detailed Description

Service module for support of SMC regridding and interpolation.

For SMC grids, four types of output are possible:

1. Flat grid (seapoint) output of SMC cells with associated cell size variables (cx and cy). Requires extra effort to plot as grid is not regular.
2. Regular, uniformly gridded output to a specified output grid. This is achieved by area averaging of the SMC cells. The output grid will be aligned with the SMC grid cell edges which may result in the actual output grid being slightly different to the original user request. A land/sea mask is created by keeping track of the cell coverage and setting cells with total coverage of <50% UNDEF.
3. [Experimental] Arbitrary regualar grid re-gridding using indices and weights generated from WW3_SMCINT*. Uses the local gradient within the grid cell and distance between cell centres to interpolate.
4. [Experimental] As type 3, but with no interpolation - value from surrounding SMC cell only.

* The ww3_smcint program is experimental and not yet included in the official WW3 distribution; it is currently part of the UK Met Office's suite of internal tools.

Remarks

Note - directional fields are expected to be passed to routines with units of radians (cartesian convention). They will be OUTPUT in units of degrees (nautical convention).

Author

Chris Bunney

Date

21-Jul-2021

Change log

Date	Ver	Comments
18-Jan-2016	4.18	Initial version
28-Sep-2016	4.18	Bug fix EXO/EYO calcs for whole domain output
05-Oct-2016	4.18	Bug fix regular grid indicies for type 2 output
29-Sep-2017	4.18	Revise calculation of indicies to ensure selected cells fall inside user selected areas.
18-Apr-2018	4.18	Added Type 3 and 4 SMC output
20-Jun-2018	4.18	Directional fields output as nautical convention (deg)
27-Jun-2018	6.05	Ported to V6
06-Jan-2021	7.12	Use ARCTC option for SMC grid.
20-Jul-2021	7.12	Fix bug where edge cells in design grid may not be matched due where SMC cell > base grid size.
21-Jul-2021	7.12	Elevated some grid variables to DOUBLE PRECISION, fixed EXO/EYO bug

Function/Subroutine Documentation

calc_interp()

subroutine w3smcomd::calc_interp

Calculates weights for SMC to arbitrary grid intepolation.

Calculates the interpolation indices and weights for regridding an SMC grid to an arbitrary regular grid. Calculated index is that of the SMC cell that contains output cell centre. Weights are the distance in metres between the output and SMC cell centres.

A future version may allow for output grids to be on a rotated pole.

Author

Chris Bunney

Date

18-Apr-2018

Definition at line 623 of file w3smcomd.F90.

 
    USE w3gdatmd, ONLY: clats
    USE constants, ONLY : dera, radius
#ifdef W3_RTD
    USE w3servmd, ONLY: w3lltoeq
    USE w3gdatmd, ONLY: polon, polat
#endif
 
    IMPLICIT NONE
    INTEGER :: IERR, I, J, ISEA, N, CFAC
    REAL :: mlon(NSEA), mlat(NSEA), olon(nxo,nyo), olat(nxo,nyo),     &
         ang(nxo,nyo), lon, lat
#ifdef W3_RTD
    REAL :: tmplon(nxo,nyo), tmplat(nxo,nyo)
#endif
 
    ! Determine smallest cell size factor:
    cfac = 2**(nrlv - 1)
 
    ! Get smallest SMC grid cells step size:
    dlat = sy / cfac
    dlon = sx / cfac
 
    ALLOCATE(xdist(nx,ny), ydist(ny,nx))
 
    ! Model lat/lons:
    DO isea = 1,nsea
      mlon(isea) = (x0-0.5*sx) + (ijkcel(1,isea) + 0.5 * ijkcel(3,isea)) * dlon
      mlat(isea) = (y0-0.5*sy) + (ijkcel(2,isea) + 0.5 * ijkcel(4,isea)) * dlat
    ENDDO
 
    ! Generate output grid cell centres:
    DO i=1,nxo
      DO j=1,nyo
        olon(i,j) = sxo + (i-1) * dxo
        olat(i,j) = syo + (j-1) * dyo
      ENDDO
    ENDDO
 
#ifdef W3_RTD
    tmplat = olat
    tmplon = olon
    print*,'Rotating coordinates'
    CALL w3lltoeq ( tmplat, tmplon, olat, olon,                       &
         ang, polat, polon, nxo*nyo )
    print*,'Rotating coordinates complete'
#endif
 
    ! Cycle over output grid points and find containing SMC cell:
    ! NOTE : BRUTE FORCE!
    nnidx(:,:) = -1
    DO i=1,nxo
      print*,i,' of ',nxo
      DO j=1,nyo
        lon = olon(i,j)
        lat = olat(i,j)
        IF(lon .LT. x0 - sx / 2) lon = lon + 360.0
        IF(lon .GT. (x0 + (nx-1) * sx) + 0.5 * sx) lon = lon - 360.0
        DO isea=1,nsea
          IF(mlon(isea) - 0.5 * ijkcel(3,isea) * dlon .LE. lon .AND.    &
               mlon(isea) + 0.5 * ijkcel(3,isea) * dlon .GE. lon .AND.    &
               mlat(isea) - 0.5 * ijkcel(4,isea) * dlat .LE. lat .AND.    &
               mlat(isea) + 0.5 * ijkcel(4,isea) * dlat .GE. lat ) THEN
            ! Match!
            nnidx(i,j) = isea
            xdist(i,j) = (lon - mlon(isea)) * dera * radius * clats(isea)
            ydist(i,j) = (lat - mlat(isea)) * dera * radius
            EXIT
          ENDIF
        ENDDO
      ENDDO
    ENDDO
 

References w3gdatmd::clats, constants::dera, dlat, dlon, dxo, dyo, nnidx, w3gdatmd::polat, w3gdatmd::polon, constants::radius, sxo, syo, w3servmd::w3lltoeq(), xdist, and ydist.

mapsta_smc()

subroutine w3smcomd::mapsta_smc

Calculates a new MAPSTA using SMC grid cell averaging.

Author

Chris Bunney

Date

02-Jul-2013

Definition at line 519 of file w3smcomd.F90.

 
    IMPLICIT NONE
 
    ! Local parameters
    INTEGER           :: I, J, IX, IY, IMX, IMY, ISEA
 
    ! Initialise coverage and output arrays:
    cov(:,:) = 0.0
    mapsmc(:,:) = 0
 
    DO isea=1,nsea
      imx = mapsf(isea,1)
      imy = mapsf(isea,2)
 
      IF(xidx(isea) .EQ. -1) cycle   ! Out of grid
 
      ! Loop over number of spanned cells:
      DO i=0, xspan(isea) - 1
        DO j=0, yspan(isea) - 1
          ix = xidx(isea) + i
          iy = yidx(isea) + j
 
          ! Spans outside of grid?
          IF(ix .GT. nxo .OR. iy .GT. nyo) cycle
 
          ! MAPSTA values: 0=Excluded, (+-)1=Sea, (+-2)=Input boundary
          ! We will just keep track of sea and non-sea points:
          IF(mapsta(imy, imx) .NE. 0) THEN
            ! Keep track of how much of cell is (wet) covered:
            cov(ix, iy) = cov(ix, iy) + wts(isea)
          ENDIF
        ENDDO
      ENDDO
 
    ENDDO
 
    ! Create coastline by masking out areas with < 50% coverage:
    DO ix=1,nxo
      DO iy=1,nyo
        IF(cov(ix,iy) .LT. 0.5) THEN
          mapsmc(ix, iy) = 0
        ELSE
          mapsmc(ix, iy) = 1
        ENDIF
      ENDDO
    ENDDO
 
    RETURN
 

References cov, w3gdatmd::mapsf, mapsmc, w3gdatmd::mapsta, w3gdatmd::nsea, nxo, nyo, wts, xidx, xspan, yidx, and yspan.

read_smcint()

subroutine w3smcomd::read_smcint

Read interpolation information from smcint.ww3.

Reads the interpolation indices and distance weights from the smcint.ww3 file generated by ww3_smcint program.

Author

Chris Bunney

Date

18-Apr-2018

Definition at line 580 of file w3smcomd.F90.

 
    USE w3servmd, ONLY: extcde
    IMPLICIT NONE
 
    ! Locals
    INTEGER :: IERR, I, J
    REAL :: PLATO, PLONO ! Not used yet....future version might allow
    ! output to a rotated pole grid...
 
    ndsmc = 50
    OPEN(ndsmc, file='smcint.ww3', status='old', form='unformatted', convert=file_endian, iostat=ierr)
    IF(ierr .NE. 0) THEN
      WRITE(*,*) "ERROR! Failed to open smcint.ww3 for reading"
      CALL extcde(1)
    ENDIF
 
    ! Header
    READ(ndsmc) nxo, nyo, sxo, syo, dxo, dyo, plono, plato
    ALLOCATE(nnidx(nxo,nyo), xdist(nxo,nyo), ydist(nxo,nyo))
 
    ! Indices and weights:
    READ(ndsmc)((nnidx(i,j), xdist(i,j), ydist(i,j),i=1,nxo),j=1,nyo)
 
    CLOSE(ndsmc)
 

References dxo, dyo, w3servmd::extcde(), file(), constants::file_endian, ndsmc, nnidx, nxo, nyo, sxo, syo, xdist, and ydist.

smc_interp()

subroutine w3smcomd::smc_interp

Generate SMC interpolation/output information.

This subroutine generates index or mask values for extraction of SMC data to either a flat grid or regular lat/lon grid, depending on the type of SMC output grid selected:

Type 1: Generates a mask for extracting only points from the user requested region.

Type 2: Calculate interpolation indices and weights for regridding the irregular SMC grid onto a regular, uniformly spaced lat/lon grid.

Author

Chris Bunney

Date

22-Oct-2015

Definition at line 143 of file w3smcomd.F90.

 
    IMPLICIT NONE
 
    ! Locals
    REAL    :: CX0, CY0   ! SW corner of origin of grid
    REAL    :: S0CHK, XSNAP, YSNAP
 
    INTEGER :: ISEA, mx, my, ixx, iyy, J
    REAL    :: lat, lon
 
    j = 1
    nsmc = 0
 
    ! Determine smallest cell size factor:
    cfac = 2**(nrlv - 1)
 
    ! Get smallest SMC grid cells step size:
    dlat = sy / cfac
    dlon = sx / cfac
    ! SW Corner of grid origin cell:
    cx0 = x0 - sx / 2.
    cy0 = y0 - sy / 2.
 
    ! Grid cell size to snap design grid to. Will be regular grid
    ! resolution for cellsize <= cfac, or cellsize for cellsize > cfac
    xsnap = sx
    ysnap = sy
    IF(celfac .gt. cfac) xsnap = celfac * dlon
    IF(celfac .gt. cfac) ysnap = celfac * dlat
 
    ! Get start lat,lon (must be aligned with SMC grid edges). Use
    ! regular grid origins if SXO or SYO is -999.9 (use full grid):
    IF(abs(sxo + 999.9) .LT. 1e-4) THEN
      sxo = cx0
    ELSE
      s0chk = cx0 + floor((sxo - cx0) / xsnap) * xsnap
      ! Ensure first grid value falls within specified range
      IF (s0chk .LT. sxo) THEN
        sxo = s0chk + xsnap
      ELSE
        sxo = s0chk
      ENDIF
    ENDIF
    IF(abs(syo + 999.9) .LT. 1e-4) THEN
      syo = cy0
    ELSE
      s0chk = cy0 + floor((syo - cy0) / ysnap) * ysnap
      ! Ensure first grid value falls within specified range
      IF (s0chk .LT. syo) THEN
        syo = s0chk + ysnap
      ELSE
        syo = s0chk
      ENDIF
    ENDIF
 
    ! Use regular grid extents for last lat/lon if user
    ! specifies -999.9 for EXO/EYO (use full grid):
    IF(abs(exo + 999.9) .LT. 1e-4) THEN
      exo = cx0 + sx * nx ! TRHC of last cell
    ENDIF
    IF(abs(eyo + 999.9) .LT. 1e-4) THEN
      eyo = cy0 + sy * ny ! TRHC of last cell
    ENDIF
 
    ! Ouput grid cell dx/dy will be integer factor of smallest
    ! SMC grid cell size:
    dxo = dlon * celfac
    dyo = dlat * celfac
 
    ! Determine number of cells in grid:
    nxo = nint((exo - sxo) / dxo)
    nyo = nint((eyo - syo) / dyo)
 
    IF(smcotype .EQ. 2) THEN
      ! Initialise all indices to "missing":
      xidx(:) = -1
      yidx(:) = -1
    ENDIF
 
    ! Loop over cell array and calculate regidding factors:
    DO isea=1, nsea
      !          ! For grids with Arctic region: make sure we don't double count
      !          ! the overlapping boundary cells. Also, don't process the arctic
      !          ! cell (which is always the last cell).
      !          ! Note: NARC contains ALL the boundary cells (global + arctic).
      !          ! whereas NGLO contains only the global boundary cells.
      !          IF(ISEA .GT. NGLO-NBAC .AND. ISEA .LT. NSEA-NARC+1) CYCLE
      IF( arctc .AND. &
           isea .GT. nglo-nbac .AND. isea .LT. nsea-narc+1) cycle
 
      ! Get grid cell size:
      mx = ijkcel(3,isea)
      my = ijkcel(4,isea)
 
      ! Determine cell lat/lon (bottom left corner of cell)
      lon = cx0 + ijkcel(1,isea) * dlon
      lat = cy0 + ijkcel(2,isea) * dlat
 
      ! For output type 1 (seapoint array), just check whether
      ! cell centre is within specified domain range, and update
      ! output mask accordingly:
      IF( smcotype .EQ. 1 ) THEN
        ! Ensure longitude ranges are aligned
        lon = lon + 0.5 * mx * dlon
        lat = lat + 0.5 * my * dlat
        IF(lon .LT. sxo) lon = lon + 360.0
        IF(lon .GT. exo) lon = lon - 360.0
 
        ! Now check if it is within range of requested domain:
        IF(lon .GE. sxo .AND. lon .LE. exo .AND.           &
             lat .GE. syo .AND. lat .LE. eyo ) THEN
          smcmask(isea) = .true.
          smcidx(j) = isea
          j = j + 1
        ENDIF
        cycle
      ENDIF ! SMCOTYPE == 1
 
      ! For output type 2 (area averaged regular grid), determine
      ! SMC grid cell location and coverage in output grid:
 
      ! Align lons
      IF(lon .LT. sxo) THEN
        lon = lon + 360.
      ENDIF
      IF(lon .GT. exo) THEN
        lon = lon - 360.
      ENDIF
 
      ! Find first SW cell in design grid:
      ! We add on 1/2 of the smallest SMC cell dlon/dlat values to ensure
      ! source grid cell ends up in the correct target grid cell (after
      ! integer trunction):
      ixx = floor((lon + 0.5*dlon - sxo) / dxo) + 1
      iyy = floor((lat + 0.5*dlat - syo) / dyo) + 1
 
      ! If we fall outside the left/bottom edge of the design grid,
      ! check for cases where the SMC cell has a lon or lat
      ! scaling factor > cfac (design grid is assumed to align
      ! its origin with cells of size cfac). For such cells,
      ! keep moving the left/bottom edge up by cfac until
      ! the SW corner (possibly) matches a design grid cell.
      IF(ixx .LE. 0 .AND. ixx + mx / celfac .GT. 0) THEN
        DO WHILE(mx .GT. cfac)
          mx = mx - cfac
          lon = lon + dlon * cfac
          ixx = floor((lon + 0.5*dlon - sxo) / dxo) + 1
          IF(ixx .GT. 0) EXIT ! Found cell lon-edge in design grid
        ENDDO
      ENDIF
      IF(iyy .LE. 0 .AND. iyy + my / celfac .GT. 0) THEN
        DO WHILE(my .GT. cfac)
          my = my - cfac
          lat = lat + dlat * cfac
          iyy = floor((lat + 0.5*dlat - syo) / dyo) + 1
          IF(iyy .GT. 0) EXIT ! Found cell lat-edge in design grid
        ENDDO
      ENDIF
 
      ! If SMC cell definitely out of design grid domain, then cycle.
      IF(ixx .LE. 0 .OR. ixx .GT. nxo .OR.                          &
           iyy .LE. 0 .OR. iyy .GT. nyo) THEN
        xidx(isea) = -1
        yidx(isea) = -1
        cycle
      ENDIF
 
      xidx(isea) = ixx
      yidx(isea) = iyy
      nsmc = nsmc + 1
      smcidx(nsmc) = isea
 
      ! find out how many cells it covers in the x/y directions:
      xspan(isea) = max(1, int(mx / celfac))
      yspan(isea) = max(1, int(my / celfac))
 
      ! Do a bit of error checking (non fatal - just produced warning):
      IF(xspan(isea) .GT. 1) THEN
        IF(abs((sxo+(ixx-1)*dxo) - lon) .GT. dxo/100.0) THEN
          print*, 'Potential problem with SMC grid cell span:'
          print*, xspan(isea), float(mx) / celfac
          print*, lon,lat
          print*, sxo+(ixx-1)*dxo,syo+iyy*dyo,dxo,dyo
          print*, "diff:", (sxo+(ixx-1)*dxo) - lon
        ENDIF
      ENDIF
 
      ! calc cell weight in relation to output grid:
      wts(isea) = min(1., dble(min(celfac, mx) * min(celfac, my)) / &
           (celfac**2))
 
    ENDDO
 
    ! Reset SXO and SYO to be the cell-centre (currently cell SW edge):
    sxo = sxo + 0.5 * dxo
    syo = syo + 0.5 * dyo
 

References w3gdatmd::arctc, celfac, cfac, dlat, dlon, dxo, dyo, exo, eyo, w3gdatmd::ijkcel, w3gdatmd::narc, w3gdatmd::nbac, w3gdatmd::nglo, w3gdatmd::nrlv, w3gdatmd::nsea, nsmc, w3gdatmd::nx, nxo, w3gdatmd::ny, nyo, smcidx, smcmask, smcotype, w3gdatmd::sx, sxo, w3gdatmd::sy, syo, wts, w3gdatmd::x0, xidx, xspan, w3gdatmd::y0, yidx, and yspan.

w3s2xy_smc()

subroutine w3smcomd::w3s2xy_smc	(	real, dimension(:), intent(in)	S,
		real, dimension(nxo,nyo), intent(out)	XY,
		logical, optional	DIR
	)

Entry point for SMC version of W3S2XY.

Dispatches to regridding subroutine based on SMCOTYPE. Optional DIR logical specifies whether field is a directional value; in which case it will be decomposed into u/v components prior to any interpolation.

Parameters

[in]	S	Input array on SMC grid
[out]	XY	Output array to store interpolated 2D field
[in]	DIR	(Optional) Set to .TRUE. if S is a directional field

Author

Chris Bunney

Date

18-Apr-2018

Definition at line 817 of file w3smcomd.F90.

 
    IMPLICIT NONE
 
    REAL, INTENT(IN)  :: S(:)
    REAL, INTENT(OUT) :: XY(NXO,NYO)
    LOGICAL, OPTIONAL :: DIR
 
    LOGICAL           :: DIRN
    INTEGER           :: ISEA
 
    IF(PRESENT(dir)) THEN
      dirn = dir
    ELSE
      dirn = .false.
    ENDIF
 
    IF(smcotype .EQ. 1) THEN
      ! Flat sea point array
      xy(:,1) = pack(s, smcmask)
      IF(dirn) THEN
        ! Convert to nautical convention in degrees
        DO isea=1,nxo
          IF(xy(isea,1) .NE. undef) THEN
            xy(isea,1) = mod(630. - rade * xy(isea,1), 360.)
          ENDIF
        ENDDO
      ENDIF
    ELSEIF(smcotype .EQ. 2) THEN
      ! Regular gridded SMC cells
      IF(dirn) THEN
        CALL w3s2xy_smcrg_dir(s, xy)
      ELSE
        CALL w3s2xy_smcrg(s, xy)
      ENDIF
    ELSEIF(smcotype .EQ. 3) THEN
      ! Regridded to arbitrary regular grid with interpolation
      CALL w3s2xy_smcnn_int(s, xy, dirn)
    ELSEIF(smcotype .EQ. 4) THEN
      ! Regridded to arbitrary regular grid - no interpolation
      CALL w3s2xy_smcnn(s, xy, dirn)
    ELSE
      WRITE(*,*) "Uknonwn SMC type!", smcotype
      ! Unknown SMC type!
      stop
    ENDIF
 

References constants::rade, smcmask, smcotype, constants::undef, w3s2xy_smcnn(), w3s2xy_smcnn_int(), w3s2xy_smcrg(), and w3s2xy_smcrg_dir().

w3s2xy_smcnn()

subroutine w3smcomd::w3s2xy_smcnn	(	real, dimension(:), intent(in)	S,
		real, dimension(nxo,nyo), intent(out)	XY,
		logical, intent(in)	DIRN
	)

Fill regular grid using nearest SMC point data.

Directional fields (DIRN=True) will be assumed to be in radians and will be converted to degrees in nautical convention.

Parameters

[in]	S	Input array on SMC grid
[out]	XY	Output array to store interpolated 2D field
[in]	DIRN	Set to .TRUE. if S is a directional field

Author

Chris Bunney

Date

18-Apr-2018

Definition at line 712 of file w3smcomd.F90.

 
    IMPLICIT NONE
 
    ! Input parameters:
    REAL, INTENT(IN)    :: S(:)        ! Inupt array
    REAL, INTENT(OUT)   :: XY(NXO,NYO) ! Output data
    LOGICAL, INTENT(IN) :: DIRN        ! Directional field?
 
    ! Local parameters
    INTEGER           :: I, J, IX, IY, ISEA, ISMC
    DO ix = 1,nxo
      DO iy = 1,nyo
        isea = nnidx(ix,iy) ! Nearest neighbour SMC point
        IF(isea .EQ. -1) THEN
          ! Land
          xy(ix,iy) = undef
        ELSE
          IF(s(isea) .EQ. undef) THEN
            ! Set undefined sea points to NOVAL
            xy(ix,iy) = noval
          ELSE
            xy(ix,iy) = s(isea)
            IF(dirn) THEN
              ! Convert direction fields to degrees nautical
              xy(ix,iy) = mod(630. - rade * xy(ix,iy), 360.0)
            ENDIF
          ENDIF
        ENDIF
      ENDDO
    ENDDO
 

References nnidx, noval, constants::rade, and constants::undef.

Referenced by w3s2xy_smc().

w3s2xy_smcnn_int()

subroutine w3smcomd::w3s2xy_smcnn_int	(	real, dimension(:), intent(in)	S,
		real, dimension(nxo,nyo), intent(out)	XY,
		logical, intent(in)	DIRN
	)

Nearest neighbour interpolation.

Fill regular grid using nearest SMC point data and interpolate output value based on local gradient and distance between grid cell centres.

Directional fields (DIRN=True) will be assumed to be in radians and will be converted to degrees in nautical convention.

Parameters

[in]	S	Input array on SMC grid
[out]	XY	Output array to store interpolated 2D field
[in]	DIRN	Set to .TRUE. if S is a directional field

Author

Chris Bunney

Date

18-Apr-2018

Definition at line 763 of file w3smcomd.F90.

 
    USE w3psmcmd, ONLY: smcgradn
    IMPLICIT NONE
 
    ! Input parameters:
    REAL, INTENT(IN)    :: S(:)        ! Input array
    REAL, INTENT(OUT)   :: XY(NXO,NYO) ! Output array
    LOGICAL, INTENT(IN) :: DIRN        ! Directional field?
 
    ! Locals
    INTEGER           :: I, J, IX, IY, ISEA, ISMC
    REAL              :: CVQ(-9:NSEA)
    REAL              :: GrdX(NSEA), GrdY(NSEA)
 
    ! Calculate local gradients:
    cvq(1:nsea) = s ! Need to copy S into array with bounds starting at -9
    CALL smcgradn(cvq, grdx, grdy, 0)
 
    ! Interpolate:
    DO ix = 1,nxo
      DO iy = 1,nyo
        isea = nnidx(ix,iy) ! Nearest neighbour SMC point
        IF(isea .EQ. -1) THEN
          xy(ix,iy) = undef
        ELSE
          ! Interpolate using local gradient and distance from cell centre:
          xy(ix,iy) = s(isea) + grdx(isea) * xdist(ix,iy) + grdy(isea) * ydist(ix,iy)
          IF(dirn) THEN
            ! Convert direction fields to degrees nautical
            xy(ix,iy) = mod(630. - rade * xy(ix,iy), 360.0)
          ENDIF
        ENDIF
      ENDDO
    ENDDO
 

References nnidx, constants::rade, w3psmcmd::smcgradn(), constants::undef, xdist, and ydist.

Referenced by w3s2xy_smc().

w3s2xy_smcrg()

subroutine w3smcomd::w3s2xy_smcrg	(	real, dimension(:), intent(in)	S,
		real, dimension(nxo,nyo), intent(out)	XY
	)

Regrid SMC data onto a regular grid.

Regrids scalar data from the SMC grid onto a regular grid. Uses pre-calculated grid indices and weights generated from the smc_interp() subroutine.

Remarks

If source field is directional data, use the w3s2xy_smcrg_dir() subroutine instead.

Parameters

[in]	S	Source field, on SMC grid.
[out]	XY	Storage for regridded field; must be 2D array with dimensions of (NXO,NYO).

Author

Chris Bunney

Date

02-Jul-2013

Definition at line 360 of file w3smcomd.F90.

 
    IMPLICIT NONE
 
    ! Input parameters:
    REAL, INTENT(IN)  :: S(:)
    REAL, INTENT(OUT) :: XY(NXO,NYO)
 
    ! Local parameters
    INTEGER           :: I, J, IX, IY, ISEA, ISMC
 
    ! Initialise coverage and output arrays:
    cov(:,:) = 0.0
    xy(:,:) = 0.0
 
    DO ismc=1,nsmc
      isea = smcidx(ismc)
 
      IF(s(isea) .EQ. undef) cycle   ! MDI
 
      ! Loop over number of spanned cells:
      DO i=0, xspan(isea) - 1
        DO j=0, yspan(isea) - 1
          ix = xidx(isea) + i
          iy = yidx(isea) + j
 
          ! Spans outside of grid?
          IF(ix .GT. nxo .OR. iy .GT. nyo) cycle
 
          ! Interpolate:
          xy(ix, iy) = xy(ix, iy) + s(isea) * wts(isea)
 
          ! Keep track of how much of cell is (wet) covered:
          cov(ix, iy) = cov(ix, iy) + wts(isea)
        ENDDO
      ENDDO
 
    ENDDO
 
    ! Create coastline by masking out areas with < 50% coverage:
    DO ix=1,nxo
      DO iy=1,nyo
        IF(mapsmc(ix,iy) .EQ. 0) THEN
          ! Make land point
          xy(ix,iy) = undef
        ELSE IF(cov(ix,iy) .LT. 0.5) THEN
          ! More than half of cell has UNDEF values - set to NOVAL:
          xy(ix,iy) = noval
        ELSE IF(cov(ix,iy) .LT. 1.0) THEN
          ! If coverage < 1.0, scale values back to full cell coverage.
          ! Without this step, points around coast could end up with lower
          ! waveheights due to weights not summing to 1.0:
          xy(ix,iy) = xy(ix,iy) * ( 1.0 / cov(ix,iy) )
        ENDIF
      ENDDO
    ENDDO
 
    RETURN
 

References cov, mapsmc, noval, nsmc, smcidx, constants::undef, wts, xidx, xspan, yidx, and yspan.

Referenced by w3s2xy_smc().

w3s2xy_smcrg_dir()

subroutine w3smcomd::w3s2xy_smcrg_dir	(	real, dimension(:), intent(in)	S,
		real, dimension(nxo,nyo), intent(out)	XY
	)

Regrid directional SMC data onto a regular grid.

Regrids directioanl scalar data from the SMC grid onto a regular grid. Uses pre-calculated grid indices and weights generated from the smc_interp() subroutine.

Remarks

Functionality as per w3s2xy_smc(), but decomposes the field into u/v components first to ensure proper area averaging of directional data (handles cyclic transition between 359 -> 0 degrees).

Parameters

[in]	S	Directional source field, on SMC grid.
[out]	XY	Storage for regridded field; must be 2D array with dimensions of (NXO,NYO).

Author

Chris Bunney

Date

02-Jul-2013

Definition at line 439 of file w3smcomd.F90.

 
    IMPLICIT NONE
 
    ! Input parameters:
    REAL, INTENT(IN)  :: S(:)
    REAL, INTENT(OUT) :: XY(NXO,NYO)
 
    ! Local parameters
    INTEGER           :: I, J, IX, IY, ISEA, ISMC
    REAL, ALLOCATABLE :: AUX1(:,:), AUX2(:,:)
    REAL              :: COSS, SINS
 
    ! Initialise coverage and output arrays:
    ALLOCATE(aux1(nxo,nyo),aux2(nxo,nyo))
    cov(:,:) = 0.0
    xy(:,:) = 0.0
    aux1(:,:) = 0.0
    aux2(:,:) = 0.0
 
    DO ismc=1,nsmc
      isea = smcidx(ismc)
 
      IF(s(isea) .EQ. undef) cycle   ! MDI
      coss = cos(s(isea))
      sins = sin(s(isea))
 
      ! Loop over number of spanned cells:
      DO i=0, xspan(isea) - 1
        DO j=0, yspan(isea) - 1
          ix = xidx(isea) + i
          iy = yidx(isea) + j
 
          ! Spans outside of grid?
          IF(ix .GT. nxo .OR. iy .GT. nyo) cycle
 
          ! Interpolate:
          !XY(IX, IY) = XY(IX, IY) + S(ISEA) * WTS(ISEA)
          aux1(ix, iy) = aux1(ix, iy) + coss * wts(isea)
          aux2(ix, iy) = aux2(ix, iy) + sins * wts(isea)
 
          ! Keep track of how much of cell is (wet) covered:
          cov(ix, iy) = cov(ix, iy) + wts(isea)
        ENDDO
      ENDDO
 
    ENDDO
 
    ! Create coastline by masking out areas with < 50% coverage:
    DO ix=1,nxo
      DO iy=1,nyo
        IF(mapsmc(ix,iy) .EQ. 0) THEN
          ! Make land point
          xy(ix,iy) = undef
        ELSE IF(cov(ix,iy) .LT. 0.5) THEN
          ! More than half of cell has UNDEF values - set to NOVAL
          xy(ix,iy) = noval
        ELSE IF(cov(ix,iy) .LT. 1.0) THEN
          ! If coverage < 1.0, scale values back to full cell coverage.
          ! Without this step, points around coast could end up with lower
          ! waveheights due to weights not summing to 1.0:
          xy(ix,iy) = atan2(aux2(ix,iy), aux1(ix,iy))
          xy(ix,iy) = mod(630. - rade * xy(ix,iy), 360. )
        ELSE
          xy(ix,iy) = atan2(aux2(ix,iy), aux1(ix,iy))
          xy(ix,iy) = mod(630. - rade * xy(ix,iy), 360. )
        ENDIF
      ENDDO
    ENDDO
 
    RETURN
 

References cov, mapsmc, noval, nsmc, constants::rade, smcidx, constants::undef, wts, xidx, xspan, yidx, and yspan.

Referenced by w3s2xy_smc().

Variable Documentation

celfac

integer w3smcomd::celfac

Output grid cell scaling factor; should be an integer power of 2.

Definition at line 92 of file w3smcomd.F90.

  INTEGER              :: CELFAC

Referenced by smc_interp(), and w3ounf().

cfac

integer w3smcomd::cfac

SMC scaling factor (number of levels)

Definition at line 108 of file w3smcomd.F90.

  INTEGER              :: CFAC

Referenced by smc_interp().

cov

real, dimension(:,:), allocatable w3smcomd::cov

Wet fraction (coverage) of cell.

Definition at line 98 of file w3smcomd.F90.

  REAL, ALLOCATABLE    :: COV(:,:)

Referenced by mapsta_smc(), w3s2xy_smcrg(), and w3s2xy_smcrg_dir().

dlat

real w3smcomd::dlat

Base longitude cell size.

Definition at line 106 of file w3smcomd.F90.

  REAL                 :: DLAT

Referenced by calc_interp(), and smc_interp().

dlon

real w3smcomd::dlon

Base latitude cell size.

Definition at line 107 of file w3smcomd.F90.

  REAL                 :: DLON

Referenced by calc_interp(), and smc_interp().

dxo

double precision w3smcomd::dxo

Output grid cell longitude size.

Definition at line 81 of file w3smcomd.F90.

  DOUBLE PRECISION     :: DXO

Referenced by calc_interp(), read_smcint(), and smc_interp().

dyo

double precision w3smcomd::dyo

Output grid cell latitude size.

Definition at line 82 of file w3smcomd.F90.

  DOUBLE PRECISION     :: DYO

Referenced by calc_interp(), read_smcint(), and smc_interp().

exo

double precision w3smcomd::exo

Output grid final longitude.

Definition at line 79 of file w3smcomd.F90.

  DOUBLE PRECISION     :: EXO

Referenced by smc_interp(), and w3ounf().

eyo

double precision w3smcomd::eyo

Output grid final latitude.

Definition at line 80 of file w3smcomd.F90.

  DOUBLE PRECISION     :: EYO

Referenced by smc_interp(), and w3ounf().

mapsmc

integer, dimension(:,:), allocatable w3smcomd::mapsmc

Regridded MAPSTA.

Definition at line 99 of file w3smcomd.F90.

  INTEGER, ALLOCATABLE :: MAPSMC(:,:)

Referenced by mapsta_smc(), w3s2xy_smcrg(), and w3s2xy_smcrg_dir().

ndsmc

integer w3smcomd::ndsmc

ww3_smcint file unit number

Definition at line 116 of file w3smcomd.F90.

  INTEGER              :: NDSMC

Referenced by read_smcint().

nnidx

integer, dimension(:,:), allocatable w3smcomd::nnidx

Nearest neighbour SMC point to regular grid.

Definition at line 113 of file w3smcomd.F90.

  INTEGER, ALLOCATABLE :: NNIDX(:,:)

Referenced by calc_interp(), read_smcint(), w3s2xy_smcnn(), and w3s2xy_smcnn_int().

noval

real w3smcomd::noval

Fill value for seapoints with no value.

Definition at line 110 of file w3smcomd.F90.

  REAL                 :: NOVAL

Referenced by w3ounf(), w3s2xy_smcnn(), w3s2xy_smcrg(), and w3s2xy_smcrg_dir().

nsmc

integer w3smcomd::nsmc

Number of SMC cells used in regridding.

Definition at line 120 of file w3smcomd.F90.

  INTEGER              :: NSMC

Referenced by smc_interp(), w3s2xy_smcrg(), and w3s2xy_smcrg_dir().

nxo

integer w3smcomd::nxo

Output grid number of longitude cells.

Definition at line 83 of file w3smcomd.F90.

  INTEGER              :: NXO

Referenced by mapsta_smc(), read_smcint(), and smc_interp().

nyo

integer w3smcomd::nyo

Output grid number of latitude cells.

Definition at line 84 of file w3smcomd.F90.

  INTEGER              :: NYO

Referenced by mapsta_smc(), read_smcint(), and smc_interp().

smccx

integer, dimension(:), allocatable w3smcomd::smccx

SMC grid definition.

Longitude cell size factors

Definition at line 104 of file w3smcomd.F90.

  INTEGER, ALLOCATABLE :: SMCCX(:)

smccy

integer, dimension(:), allocatable w3smcomd::smccy

Latitude cell size factors.

Definition at line 105 of file w3smcomd.F90.

  INTEGER, ALLOCATABLE :: SMCCY(:)

smcidx

integer, dimension(:), allocatable w3smcomd::smcidx

Indices of SMC cells within output grid domain.

Definition at line 101 of file w3smcomd.F90.

  INTEGER, ALLOCATABLE :: SMCIDX(:)

Referenced by smc_interp(), w3s2xy_smcrg(), and w3s2xy_smcrg_dir().

smcmask

logical, dimension(:), allocatable w3smcomd::smcmask

Mask for type 1 output (flat array)

Definition at line 100 of file w3smcomd.F90.

  LOGICAL, ALLOCATABLE :: SMCMASK(:)

Referenced by smc_interp(), and w3s2xy_smc().

smcnout

integer w3smcomd::smcnout

Number of SMC output cells.

Definition at line 119 of file w3smcomd.F90.

  INTEGER              :: SMCNOUT

smcotype

integer w3smcomd::smcotype

Type of SMC output: 1=seapoint grid of SMC cells; 2=regridding to regular grid; 3=interpolation to arbtrary grid; 4=nearest neighbour interpolation to arbitrary grid.

Definition at line 90 of file w3smcomd.F90.

  INTEGER              :: SMCOTYPE

Referenced by w3ounfmetamd::init_meta(), smc_interp(), w3ounf(), and w3s2xy_smc().

sxo

double precision w3smcomd::sxo

Output grid longitude origin.

Definition at line 77 of file w3smcomd.F90.

  DOUBLE PRECISION     :: SXO

Referenced by calc_interp(), read_smcint(), smc_interp(), and w3ounf().

syo

double precision w3smcomd::syo

Output grid latitude origin.

Definition at line 78 of file w3smcomd.F90.

  DOUBLE PRECISION     :: SYO

Referenced by calc_interp(), read_smcint(), smc_interp(), and w3ounf().

wts

real, dimension(:), allocatable w3smcomd::wts

Regridding weights.

Definition at line 97 of file w3smcomd.F90.

  REAL, ALLOCATABLE    :: WTS(:)

Referenced by mapsta_smc(), smc_interp(), w3s2xy_smcrg(), and w3s2xy_smcrg_dir().

xdist

real, dimension(:,:), allocatable w3smcomd::xdist

Lng.

distance to nearest neighbour

Definition at line 114 of file w3smcomd.F90.

  REAL, ALLOCATABLE    :: XDIST(:,:)

Referenced by calc_interp(), read_smcint(), and w3s2xy_smcnn_int().

xidx

integer, dimension(:), allocatable w3smcomd::xidx

X-indices of SMC cells in regular grid.

Definition at line 93 of file w3smcomd.F90.

  INTEGER, ALLOCATABLE :: XIDX(:)

Referenced by mapsta_smc(), smc_interp(), w3s2xy_smcrg(), and w3s2xy_smcrg_dir().

xspan

integer, dimension(:), allocatable w3smcomd::xspan

Number of longitude cells SMC cell spans.

Definition at line 95 of file w3smcomd.F90.

  INTEGER, ALLOCATABLE :: XSPAN(:)

Referenced by mapsta_smc(), smc_interp(), w3s2xy_smcrg(), and w3s2xy_smcrg_dir().

ydist

real, dimension(:,:), allocatable w3smcomd::ydist

Lat.

distance to nearest neighbour

Definition at line 115 of file w3smcomd.F90.

  REAL, ALLOCATABLE    :: YDIST(:,:)

Referenced by calc_interp(), read_smcint(), and w3s2xy_smcnn_int().

yidx

integer, dimension(:), allocatable w3smcomd::yidx

Y-Indices of SMC cells in regular grid.

Definition at line 94 of file w3smcomd.F90.

  INTEGER, ALLOCATABLE :: YIDX(:)

Referenced by mapsta_smc(), smc_interp(), w3s2xy_smcrg(), and w3s2xy_smcrg_dir().

yspan

integer, dimension(:), allocatable w3smcomd::yspan

Number of longitude cells SMC cell spans.

Definition at line 96 of file w3smcomd.F90.

  INTEGER, ALLOCATABLE :: YSPAN(:)

Referenced by mapsta_smc(), smc_interp(), w3s2xy_smcrg(), and w3s2xy_smcrg_dir().