Start | Index | Overview • PREV | UP | NEXT The actual \(CO_2\) concentration in the atmosphere is calculated by a linear function based on the \(CO_2\) concentration (cStartValue) in the start year (cStartYear) and the slope (cSlope).
\[ \begin{equation} CO_2(Year) = Slope \cdot (Year-StartYear) + StartValue \label{co2} \end{equation} \]The light use efficiency LUE is calculated in dependence of \(CO_2\) by the formula:
\[ \begin{eqnarray} LUE(CO_2) & = & \lambda \frac{CO_2}{CO_2 +b_1 e^{-b_2 CO_2}} \label{lue} \\ lambda & = & 100 g MJ^{-1} \end{eqnarray} \]where b1 and b2 are unitless coefficients which determine the shape of the curve and are 6928 and -0.0014 respectively by default.
Finally the LUE-curve is stretched by a factor f so that it meets the reference LUE (cReferenceLueValue) value at a reference \(CO_2\) concentration (cReferenceCo2Value).
\[ \begin{eqnarray} f & = & \frac{LUE(ReferenceCO_2Value)}{ReferenceLueValue} \label{factor} \\ LUE & = & LUE(CO_2(Year)) \cdot f \label{finallue} \end{eqnarray} \]If you want to switch of the \(CO_2\) effect (e.g. if you use want to use the same solution with projects to calculate with and without \(CO_2\) effect), then you can parameterize the component, so that the calculated LUE corresponds the given one:
For clarity reasons however, it is recommended to use different solutions and to remove the SimComponent from the solution, if you don't want to calculate \(CO_2\) effect.
Stockle, C.O., Williams, J.R., Rosenberg, N.J., Jones, C.A., 1992. A method for estimating the direct and climatic effects of rising atmospheric carbon dioxide on growth and yield of crops, Agr. Sys. 38 (3), 225–238. See http://dx.doi.org/10.1016/0308-521X(92)90067-X
| Content Type | Name | Description | Data Type | Unit | Min Value | Max Value | Default Value |
|---|---|---|---|---|---|---|---|
| constant | cReferenceCo2Value | Used to rescale the curve to meet the reference point \(\eqref{factor}\). | DOUBLE | ppm | 0.0 | 2000.0 | 350.0 |
| constant | cReferenceLueValue | Used to rescale the curve to meet the reference point \(\eqref{factor}\). | DOUBLE | g/MJ | 0.0 | 10.0 | 3.0 |
| constant | cSlope | Slope to calculate CO2 amount of given year by linear function in \(\eqref{co2}\). | DOUBLE | ppm/a | -1000.0 | 1000.0 | 3.5 |
| constant | cStartValue | Reference CO2 amount of the StartYear, starting point of the line \(\eqref{co2}\) | DOUBLE | ppm | 0.0 | 2000.0 | 350.0 |
| constant | cStartYear | Reference year, starting point of the line \(\eqref{co2}\) | INT | a | 0 | 10000 | 1990 |
| constant | c_b1 | Parameter \(b_1\) to dertemine the shape of curve \(\eqref{lue}\) | DOUBLE | 1 | 0.0 | 1000000.0 | 6928.0 |
| constant | c_b2 | Parameter \(b_2\) to determine the shape of curve \(\eqref{lue}\) | DOUBLE | 1 | -10.0 | 10.0 | -0.0014 |
| out | LUE | Light use efficiency dependend on \(CO_2\) \(\eqref{finallue}\) | DOUBLE | g/MJ | 0.0 | 20.0 | - |