!-------------------------------------- LICENCE BEGIN ------------------------------------
!Environment Canada - Atmospheric Science and Technology License/Disclaimer,
! version 3; Last Modified: May 7, 2008.
!This is free but copyrighted software; you can use/redistribute/modify it under the terms
!of the Environment Canada - Atmospheric Science and Technology License/Disclaimer
!version 3 or (at your option) any later version that should be found at:
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!
!This software is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
!without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
!See the above mentioned License/Disclaimer for more details.
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!CANADA, H9P 1J3; or send e-mail to service.rpn@ec.gc.ca
!-------------------------------------- LICENCE END --------------------------------------
! #############################################################
SUBROUTINE COEF_VER_INTERP_LIN2D(PZ1,PZ2,KKLIN,PCOEFLIN,OLEUG),1
! #############################################################
!
!!**** from *VER_INTERP_LIN* - vertical linear interpolation
!! (only the 2D vertical linear interpolation)
!!
!! PURPOSE
!! -------
! This function computes the interpolation coefficient XCOEFLIN
! of the level XKLIN of grid PZ1 which is just under the points of
! grid PZ2 (respectively called hereafter 'initial' and 'target'),
! in order to perform linear interpolations between these 2 grids.
!
! CAUTION:
! * The interpolation occurs on the WHOLE grid. Therefore, one must
! only give as argument to this function the inner points of the domain,
! particularly for the vertical grid, where there is no physical information
! under the ground or at and over H.
! * The level numbers must increase from bottom to top.
!!
!!** METHOD
!! ------
!! two extrapolations are possible: with the two or four nearest points.
!!
!! Interpolation with 2 points:
!!
!! If there is less than two points on one side, the interpolation is linear.
!!
!! EXTERNAL
!! --------
!!
!! IMPLICIT ARGUMENTS
!! ------------------
!!
!! REFERENCE
!! ---------
!!
!!
!! AUTHOR
!! ------
!!
! V.Masson Meteo-France
!!
!! MODIFICATIONS
!! -------------
!! Original 18/07/97
!! 20/01/98 use explicit arguments
!! P Jabouille 20/12/02 no extrapolation under the ground
!! S. Malardel 11/2003 bug of no extrapolation under the ground
!! V. Masson 10/2003 no extrapolation above top
!! A. Lemonsu 04/2004 only 2D vertical linear interpolation
!-------------------------------------------------------------------------------
!
!* 0. DECLARATIONS
! ------------
!
USE MODD_VER_INTERP_LIN
!
IMPLICIT NONE
!
!* 0.1 Declaration of arguments
! ------------------------
REAL, DIMENSION(:,:), INTENT(IN) :: PZ1 ! altitudes of the points of the
! initial grid
REAL, DIMENSION(:,:), INTENT(IN) :: PZ2 ! altitudes of the points of the
! target grid
INTEGER,DIMENSION(:,:), INTENT(OUT), OPTIONAL :: KKLIN ! number of the level
! of the data to be interpolated
REAL, DIMENSION(:,:), INTENT(OUT), OPTIONAL :: PCOEFLIN ! interpolation
! coefficient
LOGICAL,OPTIONAL, INTENT(IN) :: OLEUG ! for linear extrapolation under the ground
!
!
!* 0.2 Declaration of local variables
! ------------------------------
!
REAL, DIMENSION(1,SIZE(PZ1,1),SIZE(PZ1,2)) :: ZZ1 ! altitudes of the points of the
! initial grid
REAL, DIMENSION(1,SIZE(PZ2,1),SIZE(PZ2,2)) :: ZZ2 ! altitudes of the points of the
! target grid
INTEGER,DIMENSION(1,SIZE(KKLIN,1),SIZE(KKLIN,2)) :: IKLIN
!
REAL, DIMENSION(1,SIZE(PCOEFLIN,1),SIZE(PCOEFLIN,2)):: ZCOEFLIN
LOGICAL,DIMENSION(SIZE(ZZ1,1),SIZE(ZZ1,2),SIZE(ZZ1,3)):: GLEVEL
INTEGER :: JK2,JI,JJ
INTEGER,DIMENSION(SIZE(ZZ1,1),SIZE(ZZ1,2)) :: ILEVEL
INTEGER,DIMENSION(SIZE(ZZ1,1),SIZE(ZZ1,2)) :: IUNDER
REAL :: ZEPS ! a small number
!-------------------------------------------------------------------------------
!
ZZ1(1,:,:) = PZ1(:,:)
ZZ2(1,:,:) = PZ2(:,:)
!
ZEPS = 1.E-12
!
!* 1. ALLOCATIONS
! -----------
!
IF ( .NOT. PRESENT(PCOEFLIN) ) THEN
! IF (ALLOCATED(NKLIN )) DEALLOCATE(NKLIN )
! IF (ALLOCATED(XCOEFLIN)) DEALLOCATE(XCOEFLIN)
IF (ASSOCIATED(NKLIN )) DEALLOCATE(NKLIN )
IF (ASSOCIATED(XCOEFLIN)) DEALLOCATE(XCOEFLIN)
!
ALLOCATE(NKLIN (1,SIZE(ZZ2,2),SIZE(ZZ2,3)))
ALLOCATE(XCOEFLIN(1,SIZE(ZZ2,2),SIZE(ZZ2,3)))
END IF
!
!-------------------------------------------------------------------------------
!
!* 2. LOOP ON THE TARGET VERTICAL GRID
! --------------------------------
!
DO JK2=1,SIZE(ZZ2,3)
!
!-------------------------------------------------------------------------------
!
!* 3. Determination of the initial level under the target level JK2
! -------------------------------------------------------------
!
GLEVEL(:,:,:) = ZZ1(:,:,:)<=SPREAD(ZZ2(:,:,JK2),3,SIZE(ZZ1,3)) *(1.-ZEPS)
ILEVEL(:,:) = COUNT(GLEVEL(:,:,:),3)
!
!* linear extrapolation under the ground
IUNDER=ILEVEL
ILEVEL(:,:) = MAX(ILEVEL(:,:),1)
!
!* linear extrapolation above the uppest level
ILEVEL(:,:) = MIN(ILEVEL(:,:),SIZE(ZZ1,3)-1)
!
IF ( .NOT. PRESENT(PCOEFLIN) ) THEN
!* save level in module
NKLIN(:,:,JK2) = ILEVEL(:,:)
ELSE
!* save level in argument
IKLIN(:,:,JK2) = ILEVEL(:,:)
END IF
!
!-------------------------------------------------------------------------------
!
!* 4. Linear interpolation coefficients
! ---------------------------------
!
IF ( .NOT. PRESENT(PCOEFLIN) ) THEN
DO JI=1,SIZE(ZZ1,1)
DO JJ=1,SIZE(ZZ1,2)
XCOEFLIN(JI,JJ,JK2)=(ZZ2(JI,JJ,JK2)-ZZ1(JI,JJ,ILEVEL(JI,JJ)+1)) &
/(ZZ1(JI,JJ,ILEVEL(JI,JJ))-ZZ1(JI,JJ,ILEVEL(JI,JJ)+1))
IF (.NOT. PRESENT(OLEUG) .AND. IUNDER(JI,JJ) < 1 ) &
XCOEFLIN(JI,JJ,JK2)=0. ! no linear extrapolation under the ground
IF (ILEVEL(JI,JJ)==SIZE(ZZ1,3)-1) & ! no extrapolation above
XCOEFLIN(JI,JJ,JK2)=MIN(XCOEFLIN(JI,JJ,JK2),1.)
ENDDO
ENDDO
ELSE
DO JI=1,SIZE(ZZ1,1)
DO JJ=1,SIZE(ZZ1,2)
ZCOEFLIN(JI,JJ,JK2)=(ZZ2(JI,JJ,JK2)-ZZ1(JI,JJ,ILEVEL(JI,JJ)+1)) &
/(ZZ1(JI,JJ,ILEVEL(JI,JJ))-ZZ1(JI,JJ,ILEVEL(JI,JJ)+1))
IF (.NOT. PRESENT(OLEUG) .AND. IUNDER(JI,JJ) < 1 ) &
ZCOEFLIN(JI,JJ,JK2)=0. ! no linear extrapolation under the ground
IF (ILEVEL(JI,JJ)==SIZE(ZZ1,3)-1) & ! no extrapolation above
ZCOEFLIN(JI,JJ,JK2)=MIN(ZCOEFLIN(JI,JJ,JK2),1.)
ENDDO
ENDDO
PCOEFLIN(:,:) = ZCOEFLIN(1,:,:)
KKLIN(:,:) = IKLIN(1,:,:)
END IF
!
!-------------------------------------------------------------------------------
!
END DO
!
!-------------------------------------------------------------------------------
!
END SUBROUTINE COEF_VER_INTERP_LIN2D