w3sln1md.F90

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#include "w3macros.h"
!/ ------------------------------------------------------------------- /
MODULE w3sln1md
  !/
  !/                  +-----------------------------------+
  !/                  | WAVEWATCH III           NOAA/NCEP |
  !/                  |           H. L. Tolman            |
  !/                  |                        FORTRAN 90 |
  !/                  | Last update :         29-May-2009 |
  !/                  +-----------------------------------+
  !/
  !/    23-Jun-2006 : Origination.                        ( version 3.09 )
  !/    29-May-2009 : Preparing distribution version.     ( version 3.14 )
  !/
  !/    Copyright 2009 National Weather Service (NWS),
  !/       National Oceanic and Atmospheric Administration.  All rights
  !/       reserved.  WAVEWATCH III is a trademark of the NWS.
  !/       No unauthorized use without permission.
  !/
  !  1. Purpose :
  !
  !     Linear wind input according to Cavaleri and Melanotte-Rizzoli
  !     (1982) filtered for low frequencies according to Tolman (1992).
  !
  !  2. Variables and types :
  !
  !  3. Subroutines and functions :
  !
  !      Name      Type  Scope    Description
  !     ----------------------------------------------------------------
  !      W3SLN1    Subr. Public   User supplied linear input.
  !     ----------------------------------------------------------------
  !
  !  4. Subroutines and functions used :
  !
  !      Name      Type  Module   Description
  !     ----------------------------------------------------------------
  !      STRACE    Subr. W3SERVMD Subroutine tracing.
  !     ----------------------------------------------------------------
  !
  !  5. Remarks :
  !
  !  6. Switches :
  !
  !     !/S  Enable subroutine tracing.
  !     !/T  Test output.
  !
  !  7. Source code :
  !/
  !/ ------------------------------------------------------------------- /
  !/
  PUBLIC
  !/
CONTAINS
  !/ ------------------------------------------------------------------- /
  SUBROUTINE w3sln1 (K, FHIGH, USTAR, USDIR, S)
    !/
    !/                  +-----------------------------------+
    !/                  | WAVEWATCH III           NOAA/NCEP |
    !/                  |           H. L. Tolman            |
    !/                  |                        FORTRAN 90 |
    !/                  | Last update :         23-Jun-2006 |
    !/                  +-----------------------------------+
    !/
    !/    23-Jun-2006 : Origination.                        ( version 3.09 )
    !/
    !  1. Purpose :
    !
    !     Linear wind input according to Cavaleri and Melanotte-Rizzoli
    !     (1982) filtered for low frequencies according to Tolman (1992).
    !
    !  2. Method :
    !
    !     The expression of Cavaleri and Melanotte-Rizzoli, converted to
    !     action spectra defined in terms of wavenumber and direction
    !     becomes
    !
    !                       -1       /     /                \ \ 4
    !       Sln  = SLNC1 * k   * max | 0., | U* cos(Dtheta) | |        (1)
    !                                \     \                / /
    !
    !                             2     -2
    !              SLNC1 = 80 RHOr  GRAV   FILT                        (2)
    !
    !     Where :
    !
    !        RHOr     Density of air dev. by density of water.
    !        U*       Wind friction velocity.
    !        Dtheta   Difference in wind and wave direction.
    !        FILT     Filter based on PM and cut-off frequencies.
    !
    !  3. Parameters :
    !
    !     Parameter list
    !     ----------------------------------------------------------------
    !       K       R.A.  I   Wavenumber for entire spectrum.
    !       FHIGH   R.A.  I   Cut-off frequency in integration (rad/s)
    !       USTAR   Real  I   Friction velocity.
    !       USDIR   Real  I   Direction of USTAR.
    !       S       R.A.  O   Source term.
    !     ----------------------------------------------------------------
    !                         *) Stored as 1-D array with dimension NTH*NK
    !
    !  4. Subroutines used :
    !
    !      Name      Type  Module   Description
    !     ----------------------------------------------------------------
    !      STRACE    Subr. W3SERVMD Subroutine tracing.
    !     ----------------------------------------------------------------
    !
    !  5. Called by :
    !
    !      Name      Type  Module   Description
    !     ----------------------------------------------------------------
    !      W3SRCE    Subr. W3SRCEMD Source term integration.
    !      W3EXPO    Subr.   N/A    Point output post-processor.
    !      GXEXPO    Subr.   N/A    GrADS point output post-processor.
    !     ----------------------------------------------------------------
    !
    !  6. Error messages :
    !
    !       None.
    !
    !  7. Remarks :
    !
    !  8. Structure :
    !
    !     See source code.
    !
    !  9. Switches :
    !
    !     !/S  Enable subroutine tracing.
    !     !/T  Test output.
    !
    ! 10. Source code :
    !
    !/ ------------------------------------------------------------------- /
    USE constants
    USE w3gdatmd, ONLY: nth, nk, ecos, esin, sig, slnc1, fspm, fshf
    USE w3odatmd, ONLY: ndse, ndst
    USE w3servmd, ONLY: extcde
#ifdef W3_S
    USE w3servmd, ONLY: strace
#endif
    !/
    IMPLICIT NONE
    !/
    !/ ------------------------------------------------------------------- /
    !/ Parameter list
    !/
    REAL, INTENT(IN)        :: K(NK), FHIGH, USTAR, USDIR
    REAL, INTENT(OUT)       :: S(NTH,NK)
    !/
    !/ ------------------------------------------------------------------- /
    !/ Local parameters
    !/
    INTEGER                 :: ITH, IK
#ifdef W3_S
    INTEGER, SAVE           :: IENT = 0
#endif
    REAL                    :: COSU, SINU, DIRF(NTH), FAC, FF1, FF2, &
         FFILT, RFR, WNF(NK)
    !/
    !/ ------------------------------------------------------------------- /
    !/
#ifdef W3_S
    CALL strace (ient, 'W3SLN1')
#endif
    !
    ! 1.  Set up factors ------------------------------------------------- *
    !
#ifdef W3_T
    WRITE (ndst,900) ustar, usdir*rade
#endif
    !
    cosu   = cos(usdir)
    sinu   = sin(usdir)
    !
    DO ith=1, nth
      dirf(ith) = max( 0. , (ecos(ith)*cosu+esin(ith)*sinu) )**4
    END DO
    !
    fac    = slnc1 * ustar**4
    ff1    = fspm * grav/(28.*ustar)
    ff2    = fshf * min(sig(nk),fhigh)
    ffilt  = min( max(ff1,ff2) , 2.*sig(nk) )
    DO ik=1, nk
      rfr    = sig(ik) / ffilt
      IF ( rfr .LT. 0.5 ) THEN
        wnf(ik) = 0.
      ELSE
        wnf(ik) = fac / k(ik) * exp(-rfr**(-4))
      END IF
    END DO
    !
    ! 2.  Compose source term -------------------------------------------- *
    !
    DO ik=1, nk
      s(:,ik) = wnf(ik) * dirf(:)
    END DO
    !
    RETURN
    !
    ! Formats
    !
#ifdef W3_T
900 FORMAT ( ' TEST W3SLN1 : USTAR, DIR :',f6.3, f6.1)
#endif
    !/
    !/ End of W3SLN1 ----------------------------------------------------- /
    !/
  END SUBROUTINE w3sln1
  !/
  !/ End of module INSLN1MD -------------------------------------------- /
  !/
END MODULE w3sln1md