net.simplace.client.simulation.lap.transformer.DayLengthTransformer
Calculates the Daylengths for a given latitude.
Takes Latitude in degrees as input
Outputs
- DOY
- Daylength in minutes
- Daylength change to previous day in minutes
Sine and cosine of latitude, maximal declination.
\[
\begin{eqnarray}
rad &=& \frac{\pi}{180}\\
sinlat &=& \sin(rad \cdot latitutde)\\
coslat &=& \cos(rad \cdot latitutde)\\
sindcm &=& \sin(rad \cdot 23.45)
\end{eqnarray}
\]
Sine and cosine of declination of the sun as function of day of year.
Calculation is taken from (G).
Some models first calculate \(dec\) as the arcsine of \(sindec\) and
then take the sine and cosine. The methods are mathematically equivalent
due to \(sin^2+cos^2=1\)
\[
\begin{eqnarray}
sindec &=& -sindcm \cos(2 \pi \frac{doy+10}{365})\\
cosdec &=& \sqrt{1-sindec^2}\\
sinld &=& sinlat \cdot sindec\\
cosld &=& coslat \cdot cosdec
\end{eqnarray}
\]
Daylength calculation.
\[
\begin{eqnarray}
arg &=& \min(1,\max(-1,\frac{sinld}{cosld}))\\
daylength &=& 12 (1 + \frac{2}{\pi} \arcsin(arg))\\
\end{eqnarray}
\]
References
(G) Goudriaan, Modeling Potential Crop Growth Processes, 1994, (revised version Nov. 2004)
public class DayLengthTransformer extends
net.simplace.simulation.io.resources.FWSimResourceTransformer {
// Public Constructors
public DayLengthTransformer(FWSimSession aSession, Element aResourceElement,
Integer aOrderNumber);
public DayLengthTransformer(FWSimSession aSession, Integer aOrderNumber);
// Public Instance Methods public HashMap createVariables(); // Defines
net.simplace.simulation.io.FWSimIOAdapter
public FWSimResourceCache getData(FWSimVarMap aVarMap)
throws MissingSimResourceException; // Defines
net.simplace.simulation.io.resources.FWSimInputAdapter
standard method from outside
public FWSimResourceCache
getData(FWSimVarMap aVarMap, FWSimResourceCache
aResourceCache) throws MissingSimResourceException;
used by test cases
- aVarMap
variable map
- aResourceCache
Cached resources (soil data)
returns delivered new data from transformer
public void fillVarMap(FWSimVarMap aVarMap);
// Defines
net.simplace.simulation.io.resources.FWSimResourceTransformer
public void updateFields(FWObservable aObservable);
// Defines
net.simplace.simulation.io.resources.FWSimResourceTransformer
}
Hierarchy: java.lang.Object - net.simplace.simulation.io.FWSimIOAdapter (net.simplace.simulation.util.FWSimFieldContainer) - net.simplace.simulation.io.resources.FWSimInputAdapter - net.simplace.simulation.io.resources.FWSimResourceTransformer - DayLengthTransformer
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