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!Environment Canada - Atmospheric Science and Technology License/Disclaimer,
! version 3; Last Modified: May 7, 2008.
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*** S/P MOMCOEF
*
#include "phy_macros_f.h"
SUBROUTINE MOMCOEF (RI,Z0TOT,Z0H,ZREF,CD,N),4
*
*
#include "impnone.cdk"
*
INTEGER N
REAL RI(N), Z0TOT(N), Z0H(N), ZREF(N), CD(N)
*
*Author
* S. Belair (April 1998)
*Revisions
* 001 B. Bilodeau (January 2001) - Automatic arrays
*
*Object
*
* Calculates the surface transfer coefficient for
* momentum.
*
*
*Arguments
*
* - Input -
* RI Richardson's number
* Z0TOT roughness length including the effect of snow
* Z0H roughness length for heat
* ZREF reference height
*
*
* - Output -
* CD drag coefficient for momentum
*
**
*
#include "consphy.cdk"
*
*
INTEGER I
*
*
************************************************************************
* AUTOMATIC ARRAYS
************************************************************************
*
AUTOMATIC ( MU , REAL , (N) )
AUTOMATIC ( CDN , REAL , (N) )
AUTOMATIC ( CMSTAR , REAL , (N) )
AUTOMATIC ( PM , REAL , (N) )
AUTOMATIC ( CM , REAL , (N) )
AUTOMATIC ( FM , REAL , (N) )
*
************************************************************************
*
*
*
*------------------------------------------------------------------------
*
*
*
*
* 1. DRAG COEFFICIENT FOR MOMENTUM TRANSFERS
* ---------------------------------------
*
* In this particular case, we now use
* the roughness length due to the coupled
* effect of vegetation and snow
* (i.e., Z0TOT)
*
* Thus, we must first recalculate ZMU,
* ZZ0T, and ZCDN
*
*
DO I=1,N
MU(I) = MAX( LOG( Z0TOT(I)/Z0H(I) ), 0.0 )
*
*
CDN(I) = (KARMAN/LOG(1.+ZREF(I)/Z0TOT(I)))**2.
*
CMSTAR(I) = 6.8741 + 2.6933*MU(I) - 0.3601*MU(I)*MU(I)
1 + 0.0154*MU(I)*MU(I)*MU(I)
PM(I) = 0.5233 - 0.0815*MU(I) + 0.0135*MU(I)*MU(I)
1 - 0.0010*MU(I)*MU(I)*MU(I)
*
CM(I) = 10.*CMSTAR(I)*CDN(I)*(1.+ZREF(I)/Z0TOT(I))**PM(I)
END DO
*
*
DO I=1,N
IF (RI(I).GT.0.0) THEN
FM(I) = 1. + 10.*RI(I) / SQRT( 1.+5.*RI(I) )
FM(I) = 1. / FM(I)
ELSE
FM(I) = 1. - 10.*RI(I) / ( 1.+CM(I)*SQRT(-RI(I)) )
END IF
*
CD(I) = CDN(I)*FM(I)
END DO
*
*
RETURN
END