w3flx5md Module Reference

Unified process to obtain friction velocity and drag when stresses are an input (from atmospheric model). More...

Functions/Subroutines
subroutine	w3flx5 (ZWND, U10, U10D, TAUA, TAUADIR, RHOAIR, UST, USTD, Z0, CD, CHARN)
	Unified process to obtain friction velocity and drag when stresses are an input (from atmospheric model). More...

Detailed Description

Unified process to obtain friction velocity and drag when stresses are an input (from atmospheric model).

Author

N.G. Valiente

J. Edward

A. Saulter

Date

01-Jul-2021

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

w3flx5()

subroutine w3flx5md::w3flx5	(	real, intent(in)	ZWND,
		real, intent(in)	U10,
		real, intent(in)	U10D,
		real, intent(in)	TAUA,
		real, intent(in)	TAUADIR,
		real, intent(in)	RHOAIR,
		real, intent(out)	UST,
		real, intent(out)	USTD,
		real, intent(out)	Z0,
		real, intent(out)	CD,
		real, intent(out)	CHARN
	)

Unified process to obtain friction velocity and drag when stresses are an input (from atmospheric model).

     UST       = SQRT(TAUA / RHOAIR)
     USTD      = TAUADIR
     CD        = (UST/U10)**2
     SQRTCDM1  = MIN(U10/UST,100.0)
     Z0        = ZWND*EXP(-KAPPA*SQRTCDM1)

Parameters

[in]	ZWND	Wind height.
[in]	U10	Wind speed.
[in]	U10D	Wind direction.
[in]	TAUA	Atmosphere total stress.
[in]	TAUADIR	Atmosphere total stress directions.
[in]	RHOAIR	Air density.
[out]	UST	Friction velocity.
[out]	USTD	Direction of friction velocity.
[out]	Z0	Z0 in profile law.
[out]	CD	Drag coefficient.
[out]	CHARN	Charnock coefficient.

Author

N.G. Valiente

J. Edward

A. Saulter

Date

01-Jul-2021

Definition at line 119 of file w3flx5md.F90.

    !/
    !/                  +-----------------------------------+
    !/                  | WAVEWATCH III           NOAA/NCEP |
    !/                  |                     |
    !/                  |           N.G. Valiente           |
    !/                  |           J. Edward               |
    !/                  |           A. Saulter              |
    !/                  |                        FORTRAN 90 |
    !/                  | Last update :         01-Jul-2021 |
    !/                  +-----------------------------------+
    !/
    !/    22-Mar-2021 : Origination.                        ( version 7.14 )
    !/    22-Mar-2021 : Enable direct use of atmospheric model wind stress
    !/                  by source terms ST6
    !/    01-Jul-2021 : Enable direct use of atmospheric model wind stress
    !/                  by source terms ST4
    !/
    !  1. Purpose :
    !
    !     Unified process to obtain friction velocity and drag when stresses are an
    !     input (from atmospheric model).
    !
    !  2. Method :
    !
    !     UST       = SQRT(TAUA / RHOAIR)
    !     USTD      = TAUADIR
    !     CD        = (UST/U10)**2
    !     SQRTCDM1  = MIN(U10/UST,100.0)
    !     Z0        = ZWND*EXP(-KAPPA*SQRTCDM1)
    !
    !  3. Parameters :
    !
    !     Parameter list
    !     ----------------------------------------------------------------
    !       ZWND    Real   I   Wind height.
    !       U10     Real   I   Wind speed.
    !       U10D    Real   I   Wind direction.
    !       TAUA    Real   I   Atm. total stress.
    !       TAUADIR Real   I   Atm. total stress direction.
    !       RHOAIR  Real   I   Air density.
    !       UST     Real   O   Friction velocity.
    !       USTD    Real   0   Direction of friction velocity.
    !       Z0      Real   O   z0 in profile law.
    !       CD      Real   O   Drag coefficient.
    !       CHARN   Real   O   Charnock 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, ONLY: kappa, grav, nu_air
    USE w3odatmd, ONLY: ndse, iaproc, naperr
    USE w3servmd, ONLY: extcde
#ifdef W3_S
    USE w3servmd, ONLY: strace
#endif
    !/
    IMPLICIT NONE
    !/
    !/ ------------------------------------------------------------------- /
    !/ Parameter list
    !/
    REAL, INTENT(IN)        :: ZWND, U10, U10D, TAUA, TAUADIR, RHOAIR
    REAL, INTENT(OUT)       :: UST, USTD, Z0, CD, CHARN
    REAL                    :: UNZ, SQRTCDM1
    !/
    !/ ------------------------------------------------------------------- /
    !/ Local parameters
    !/
#ifdef W3_S
    INTEGER, SAVE           :: IENT = 0
#endif
    !/
    !/ ------------------------------------------------------------------- /
    !/
#ifdef W3_S
    CALL strace (ient, 'W3FLX5')
#endif
    !
    ! 1.  Tests ---------------------------------------------------------- *
    !
    IF ( abs(zwnd-10.) .GT. 0.01 ) THEN
      IF ( iaproc .EQ. naperr ) WRITE (ndse,1000) zwnd
      CALL extcde (1)
    END IF
    !
    ! 2.  Computation ---------------------------------------------------- *
    !
    !
    ust    = max( 1e-4, sqrt(taua/rhoair) )
    unz    = max( 0.01 , u10 )
    cd     = (ust/unz)**2
    ustd   = tauadir
    sqrtcdm1  = min(unz/ust,100.0)
    z0        = zwnd*exp(-kappa*sqrtcdm1)
    IF (unz.GT.2.5) THEN
      charn = (z0 - 0.11 * nu_air / ust) * grav / ust**2
      charn = max( charn , 0.0095 )
      charn = min( 0.035 , charn )
    ELSE
      charn = 0.0095
    END IF
    !
    RETURN
    !
    ! Formats
    !
1000 FORMAT (/' *** WAVEWATCH III ERROR IN W3FLX5 : '/                 &
         '     HEIGHT OF WIND SHOULD BE 10m IN THIS APPROACH '/   &
         '     ZWND =',f8.2,'m'/)
    !/
    !/ End of W3FLX5 ----------------------------------------------------- /
    !/

References w3servmd::extcde(), constants::grav, w3odatmd::iaproc, constants::kappa, w3odatmd::naperr, w3odatmd::ndse, constants::nu_air, and w3servmd::strace().

Referenced by gxexpo(), w3exnc(), w3expo(), w3src4md::w3spr4(), and w3srcemd::w3srce().