!copyright (C) 2001 MSC-RPN COMM %%%RPNPHY%%%
*** S/P VEGI
*
#include "phy_macros_f.h"
SUBROUTINE VEGI ( RG, T, TS, HU, PS, W2, RGL, 1,2
1 LAI, RSMIN, GAMMA, WWILT, WFC, RS,
1 N )
*
#include "impnone.cdk"
*
INTEGER N
REAL RG(N), T(N), HU(N), PS(N), W2(N), TS(N)
REAL RGL(N), LAI(N), RSMIN(N), GAMMA(N), WWILT(N)
REAL WFC(N), RS(N)
*
*Author
* S. Belair (January 1997)
*Revisions
* 001 B. Bilodeau (January 2001)
* Automatic arrays
*
*Object
*
* Calculates the surface stomatal resistance Rs
*
*
*Arguments
*
* - Input -
* RG solar radiation
* T low-level temperature of air
* TS surface temperature
* HU low-level specific humidity of air
* PS surface pressure
* W2 soil volumetric water content
* RGL constant for the calculation of the stomatal resistance
* LAI Leaf area index
* RSMIN minimum stomatal resistance
* GAMMA other constant for RS
* WWILT volumetric water content at the wilting point
* WFC volumetric water content at the field capacity
*
* - Output -
* RS Surface or stomatal resistance
*
*
#include "consphy.cdk"
*
INTEGER I
*
*
*
************************************************************************
* AUTOMATIC ARRAYS
************************************************************************
*
AUTOMATIC ( F , REAL , (N))
AUTOMATIC ( F1 , REAL , (N))
AUTOMATIC ( F2 , REAL , (N))
AUTOMATIC ( F3 , REAL , (N))
AUTOMATIC ( F4 , REAL , (N))
AUTOMATIC ( QSAT , REAL , (N))
*
************************************************************************
*
#include "dintern.cdk"
#include "fintern.cdk"
*
*
*
*
*
*
*
*
** 1. THE 'ZF1' FACTOR
* ---------------
* This factor measures the influence
* of the photosynthetically active radiation
*
*
DO I=1,N
F(I) = 0.55*2.*RG(I) / (RGL(I)+1.E-6) /
1 ( LAI(I)+1.E-6 )
F1(I) = ( F(I) + RSMIN(I)/5000. ) / ( 1. + F(I) )
END DO
*
*
*
*
** 2. THE 'ZF2' FACTOR
* ----------------
* This factor takes into account the effect
* of the water stress on the surface
* resistance
*
* NOTE that W2 (liquid portion of soil water) is
* used here instead of W2+WF. Thus, when soil water
* freezes (W2 --> 0), ZF2 becomes small and the
* surface increases increases (no transpiration when
* soils are frozen).
*
DO I=1,N
*
*
* For humid soils, this factor does not
* increase the stomatal resistance
*
IF (W2(I).GE.WFC(I)) F2(I) = 1.0
*
*
* The stomatal resistance should be large
* when the soil is very dry
*
IF (W2(I).LT.WFC(I).AND.W2(I).LE.WWILT(I))
1 F2(I) = 1.E-5
*
*
* For intermediate soils:
*
IF (W2(I).LT.WFC(I).AND.W2(I).GT.WWILT(I))
1 F2(I) = ( W2(I)-WWILT(I) ) /
1 ( WFC(I)-WWILT(I) + 1.E-6 )
*
END DO
*
*
*
** 3. THE 'ZF3' FACTOR
* ----------------
* This factor represents the effect of
* vapor pressure deficit of the atmosphere.
* For very humid air, the stomatal resistance
* is small, whereas it increases as the
* air becomes drier.
*
*
DO I=1,N
*
QSAT(I) = FOQST( TS(I), PS(I) )
*
F3(I) = MAX( 1. - GAMMA(I)*( QSAT(I)
1 - HU(I) )*1000. , 1.E-3 )
*
END DO
*
*
*
** 4. THE 'ZF4' FACTOR
* ----------------
* This factor introduces an air temperature
* dependance on the surface stomatal resistance
*
DO I=1,N
F4(I) = MAX( 1.0 - 0.0016*(298.15-T(I))**2, 1.E-3 )
END DO
*
*
** 5. THE SURFACE STOMATAL RESISTANCE
* -------------------------------
*
DO I=1,N
RS(I) = RSMIN(I) / ( LAI(I)+1.E-6 )
1 / F1(I) / F2(I) / F3(I) / F4(I)
*
RS(I) = MIN( RS(I),5000. )
RS(I) = MAX( RS(I), 1.E-4 )
END DO
*
*
*
*
RETURN
END