w3flx3md Module Reference

FLux/stress computations according Tolman and Chalikov (1996). More...

Functions/Subroutines
subroutine	w3flx3 (ZWIND, DEPTH, FP, U, UDIR, UST, USTD, Z0, CD)
	FLux/stress computations according Tolman and Chalikov (1996). More...

Detailed Description

FLux/stress computations according Tolman and Chalikov (1996).

Cap on flux added compared to W3FLX2.

Author

H. L. Tolman

Date

20-Apr-2010

Copyright

Copyright 2009-2022 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.

Function/Subroutine Documentation

w3flx3()

subroutine w3flx3md::w3flx3	(	real, intent(in)	ZWIND,
		real, intent(in)	DEPTH,
		real, intent(in)	FP,
		real, intent(in)	U,
		real, intent(in)	UDIR,
		real, intent(inout)	UST,
		real, intent(out)	USTD,
		real, intent(out)	Z0,
		real, intent(out)	CD
	)

FLux/stress computations according Tolman and Chalikov (1996).

Cap on flux added compared to W3FLX2.

Parameters

[in]	ZWIND	Height of wind.
[in]	DEPTH	Depth.
[in]	FP	Peak frequency.
[in]	U	Wind speed.
[in]	UDIR	Wind direction.
[in,out]	UST	Friction velocity.
[out]	USTD	Direction of friction velocity.
[out]	Z0	Z0 in profile law.
[out]	CD	Drag coefficient.

Author

H. L. Tolman

Date

10-Jan-2014

Definition at line 96 of file w3flx3md.F90.

    !/
    !/                  +-----------------------------------+
    !/                  | WAVEWATCH III           NOAA/NCEP |
    !/                  |           H. L. Tolman            |
    !/                  |                        FORTRAN 90 |
    !/                  | Last update :         10-Jan-2014 |
    !/                  +-----------------------------------+
    !/
    !/    05-Jul-2006 : Origination.                        ( version 3.09 )
    !/    20-Apr-2010 : Fix INTENT of UST.                ( version 3.14.1 )
    !/    10-Jan-2014 : Add max on division by UST          ( version 4.18 )
    !/                  (This was already done for W3FLX2 on 16 Sep 2011)
    !/    10-Jan-2014 : Add a min value for FP              ( version 4.18 )
    !/
    !  1. Purpose :
    !
    !     FLux/stress computations according Tolman and Chalikov (1996).
    !     Cap on flux added compared to W3FLX2.
    !
    !  2. Method :
    !
    !  3. Parameters :
    !
    !     Parameter list
    !     ----------------------------------------------------------------
    !       ZWIND   Real   I   Hight of wind.
    !       DEPTH   Real   I   Depth.
    !       FP      Real   I   Peak frequency.
    !       U       Real   I   Wind speed.
    !       UDIR    Real   I   Wind direction.
    !       UST     Real   O   Friction velocity.
    !       USTD    Real   0   Direction of friction velocity.
    !       Z0      Real   O   z0 in profile law.
    !       CD      Real   O   Drag coefficient.
    !     ----------------------------------------------------------------
    !
    !  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.
    !     ----------------------------------------------------------------
    !
    !  6. Error messages :
    !
    !       None.
    !
    !  7. Remarks :
    !
    !  8. Structure :
    !
    !     See source code.
    !
    !  9. Switches :
    !
    !     !/S  Enable subroutine tracing.
    !
    ! 10. Source code :
    !
    !/ ------------------------------------------------------------------- /
    USE constants
    USE w3gdatmd, ONLY: nittin, cinxsi, cd_max, cap_id
    USE w3odatmd, ONLY: ndse, iaproc, naperr
    USE w3servmd, ONLY: extcde
#ifdef W3_S
    USE w3servmd, ONLY: strace
#endif
    USE w3dispmd, ONLY: dsie, n1max, ewn1
    !/
    IMPLICIT NONE
    !/
    !/ ------------------------------------------------------------------- /
    !/ Parameter list
    !/
    REAL, INTENT(IN)        :: ZWIND, DEPTH, FP, U, UDIR
    REAL, INTENT(INOUT)     :: UST
    REAL, INTENT(OUT)       :: USTD, Z0, CD
    !/
    !/ ------------------------------------------------------------------- /
    !/ Local parameters
    !/
    INTEGER                 :: I1, ITT
#ifdef W3_S
    INTEGER, SAVE           :: IENT = 0
#endif
    REAL                    :: SQRTH, SIX, R1, WNP, CP, UNZ, ALPHA, &
         RDCH, AFP
    !/
    !/ ------------------------------------------------------------------- /
    !/
#ifdef W3_S
    CALL strace (ient, 'W3FLX3')
#endif
    !
    ! 1.  Peak phase velocity -------------------------------------------- *
    !
    ! ----- start of inlined and reduced WAVNU1 -----
    !
    afp    = tpi * max( fp, 0.001)
    !
    sqrth  = sqrt( depth )
    six    = afp * sqrth
    i1     = int( six / dsie )
    IF (i1.LE.n1max) THEN
      r1 = six/dsie - real(i1)
      wnp    = ( (1.-r1)*ewn1(i1) + r1*ewn1(i1+1) ) / depth
    ELSE
      wnp    = afp * afp / grav
    END IF
    !
    ! -----  end of inlined and reduced WAVNU1  -----
    !
    cp     = afp / wnp
    !
    ! 2.  Itterative stress computation ---------------------------------- *
    !
    unz    = max( 0.01 , u )
    ustd   = udir
    !
    DO itt=1, nittin
      alpha  = 0.57 / ( cp / max(ust,0.0001) )**(1.5)
      rdch   = max( 0. ,                                           &
           log( ( zwind * grav) / ( cinxsi * sqrt(alpha) * unz**2) ) )
      cd     = 0.001 * ( 0.021 + 10.4 / (rdch**1.23+1.85) )
      ust    = sqrt(cd) * unz
      z0    = zwind * exp( -0.4 / sqrt(cd) )
    END DO
    !
    ! 3.  Apply limit to drag coefficient -------------------------------- *
    !
    IF ( cap_id .EQ. 0 ) THEN
      cd     = min( cd_max, cd )
    ELSE
      cd     = cd_max * tanh( cd / cd_max )
    END IF
    !
    ust    = sqrt(cd) * unz
    z0     = zwind * exp( -0.4 / sqrt(cd) )
    !
    RETURN
    !
    ! Formats
    !
    !/
    !/ End of W3FLX3 ----------------------------------------------------- /
    !/

References w3gdatmd::cap_id, w3gdatmd::cd_max, w3gdatmd::cinxsi, w3dispmd::dsie, w3dispmd::ewn1, w3servmd::extcde(), constants::grav, w3odatmd::iaproc, w3dispmd::n1max, w3odatmd::naperr, w3odatmd::ndse, w3gdatmd::nittin, w3servmd::strace(), and constants::tpi.

Referenced by gxexpo(), w3exnc(), w3expo(), and w3srcemd::w3srce().