c3photo.h File Reference

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Data Structures
struct	c3_str

Functions
double	fnpsvp (double Tkelvin)
double	ballBerry (double Amu, double Cappm, double Temp, double RelH, double beta0, double beta1)
struct c3_str	c3photoC (double Qp, double Tleaf, double RH, double Vcmax0, double Jmax0, double Rd0, double bb0, double bb1, double Ca, double O2, double theta, double StomWS, int ws)

Function Documentation

double ballBerry	(	double	Amu,
		double	Cappm,
		double	Temp,
		double	RelH,
		double	beta0,
		double	beta1
	)

{

        const double gbw = 1.2; /* According to Collatz et al. (1992) pg. 526*/
        const double ptotPa = 101325; /* Atmospheric pressure */

        double pwaPa, leafTk, Camf, assimn;
        double wa, pwi, wi, gswmol, Cs, acs;
        double aaa, bbb, ccc, ddd;
        double gsmol;
        double hs;

        leafTk = Temp + 273.15;
        pwi = fnpsvp(leafTk);
        pwaPa = RelH * pwi;
        Camf = Cappm * 1e-6;
        assimn = Amu * 1e-6;
  
        /* Calculate mole fraction (mixing ratio) of water vapor in */
        /* atmosphere from partial pressure of water in the atmosphere and*/
        /* the total air pressure */
        wa  = pwaPa / ptotPa;
        /* Get saturation vapor pressure for water in the leaf based on */
        /* current idea of the leaf temperature in Kelvin*/
        /* Already calculated above */
        /* Calculate mole fraction of water vapor in leaf interior */
        wi  = pwi / ptotPa;

        if(assimn < 0.0){
                /* Set stomatal conductance to the minimum value, beta0*/
                gswmol = beta0 ;
                /* Calculate leaf surface relative humidity, hs, (as fraction)*/
                /* for when C assimilation rate is <= 0*/
                /* hs = (beta0 + (wa/wi)*gbw)/(beta0 + gbw); ! unused here??*/
        }
        else{
                /* leaf surface CO2, mole fraction */
                Cs  = Camf - (1.4/gbw)*assimn;
                if(Cs < 0.0)
                        Cs = 1;
                /* Constrain the ratio assimn/cs to be > 1.e-6*/
                acs = assimn/Cs;

                if(acs < 1e-6)  acs = 1e-6;             

                /* Calculate leaf surface relative humidity, hs, from quadratic */
                /* equation: aaa*hs^2 + bbb*hs + ccc = 0 */
                /*  aaa= beta1 * assimn / cs */
                aaa = beta1 * acs;
                /*      bbb= beta0 + gbw - (beta1 * assimn / cs)*/
                bbb = beta0 + gbw - (beta1 * acs);
                ccc = -(wa / wi) * gbw - beta0;

                /* Solve the quadratic equation for leaf surface relative humidity */
                /* (as fraction) */
                ddd = bbb * bbb - 4*aaa*ccc;

                hs  = (-bbb + sqrt(ddd)) / (2* aaa);

                /* Ball-Berry equation (Collatz'91, eqn 1) */
                gswmol = beta1 * hs * acs + beta0;
        }
        gsmol = gswmol * 1000; /* converting to mmol */

        if(gsmol <= 0) gsmol = 1e-5;

        return(gsmol);
}

struct c3_str c3photoC	(	double	Qp,
		double	Tleaf,
		double	RH,
		double	Vcmax0,
		double	Jmax0,
		double	Rd0,
		double	bb0,
		double	bb1,
		double	Ca,
		double	O2,
		double	theta,
		double	StomWS,
		int	ws
	)

double fnpsvp

(

double

Tkelvin

)

                             {
        /* water boiling point = 373.16 oK*/
/* This is the Arden Buck Equation 
http://en.wikipedia.org/wiki/Arden_Buck_equation
 */
        double u, v;
        double tmp, esat;

        tmp = Tkelvin - 273.15;
        u = (18.678 - tmp/234.5)*tmp;
        v = 257.14 + tmp;
        esat = 6.1121 * exp(u/v);
        esat /= 10;

        return(esat);
}