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#include "global.h"
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#include "production3pg.h"
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#include "resourceunit.h"
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#include "species.h"
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#include "speciesresponse.h"
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#include "model.h"
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Production3PG::Production3PG()
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{
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    mResponse=0;
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}
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/**
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  This is based on the utilizable photosynthetic active radiation.
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  @sa http://iland.boku.ac.at/primary+production
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  The resulting radiation is MJ/m2       */
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inline double Production3PG::calculateUtilizablePAR(const int month) const
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{
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    // calculate the available radiation
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    // there is no production outside of the vegetation period
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    if (mResponse->absorbedRadiation()[month]==0.)
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        return 0.;
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    // see Equation (3)
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    double response = mResponse->absorbedRadiation()[month] *
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                      mResponse->vpdResponse()[month] *
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                      mResponse->soilWaterResponse()[month] *
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                      mResponse->tempResponse()[month];
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    return response;
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}
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/** calculate the alphac (=photosynthetic efficiency) for the given month.
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   this is based on a global efficiency, and modified per species.
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   epsilon is in gC/MJ Radiation
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  */
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inline double Production3PG::calculateEpsilon(const int month) const
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{
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    double epsilon = Model::settings().epsilon; // maximum radiation use efficiency
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    epsilon *= mResponse->nitrogenResponse() *
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               mResponse->co2Response();
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    return epsilon;
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}
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inline double Production3PG::abovegroundFraction() const
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{
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    double harsh =  1 - 0.8/(1 + 2.5 * mResponse->nitrogenResponse());
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    return harsh;
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}
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/** calculate the alphac (=photosynthetic efficiency) for given month.
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  @sa http://iland.boku.ac.at/primary+production */
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double Production3PG::calculate()
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{
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    Q_ASSERT(mResponse!=0);
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    // Radiation: sum over all days of each month with foliage
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    double year_raw_gpp = 0.;
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    for (int i=0;i<12;i++) {
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        mGPP[i] = 0.; mUPAR[i]=0.;
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    }
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    double utilizable_rad, epsilon;
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    // conversion from gC to kg Biomass: C/Biomass=0.5
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    const double gC_to_kg_biomass = 2. / 1000.;
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    for (int i=0;i<12;i++) {
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        utilizable_rad = calculateUtilizablePAR(i); // utilizable radiation of the month times ...
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        epsilon = calculateEpsilon(i); // ... photosynthetic efficiency ...
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        mUPAR[i] = utilizable_rad ;
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        mGPP[i] =utilizable_rad * epsilon * gC_to_kg_biomass; // ... results in GPP of the month kg Biomass/m2 (converted from gC/m2)
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        year_raw_gpp += mGPP[i]; // kg Biomass/m2
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    }
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    // calculate fac
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    mRootFraction = 1. - abovegroundFraction();
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    // global value set?
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    double dbg = GlobalSettings::instance()->settings().paramValue("gpp_per_year",0);
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    if (dbg) {
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        year_raw_gpp = dbg ;
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        mRootFraction = 0.4;
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    }
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    // year GPP/rad: kg Biomass/m2
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    mGPPperArea = year_raw_gpp;
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    return mGPPperArea; // yearly GPP in kg Biomass/m2
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}