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plantmodel [2017/11/10 09:09] (current)
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 +====== [PLANTMODEL] Section ======
 +
 +===== Purpose =====
 +To calculate the transpiration of plants, it is necessary to know the actual stomata resistance.\\
 +The stomata are active components of the plant system and react on environmental impacts such as solar input, air temperature and water availability in the soil.
 +
 +ENVI-met provides two methods for calculating the stomata resistance: A simple approach based on the work of Deardorff (1978) and a very sophisticated approach called A-gs model following the work of Jacobs (1994) (for exact references please refer to the papers available on the UNCONVERTED WINHELP MACRO:! ''​ExecFile("​www.envi-met.com"​)ENVI-met webpage''​)
 +
 +The Deardorff approach scales an explicitly given maximum value of the stomata resistance with respect to the solar input and the water availability whereas the A-gs model calculates the photosynthesis rate of the plant and concludes from that to the C02 demand and finally to the state of the stomata.
 +
 +**We recommend the use of the A-gs model as it is more plant physiologically based than the Deardorff model.**
 +
 +To choose the model, use the [PLANTMODEL] section:
 + 
 +<​file>​
 +00: [PLANTMODEL] _____________Settings for plant model
 +01: Stomata res. approach (1=Deardorff,​ 2=A-gs) ​ =2
 +02: Background CO2 concentration [ppm]           =350
 +</​file>​
 + 
 +
 +===== What do the lines mean? =====
 +
 +=== 01: Stomata res. approach (Default 2, A-gs) ===
 +Select the stomata resistance model to be used in the simulation. ​
 +
 +=== 02: Background CO2 concentration [ppm] (Default 350 ppm) ===
 +Sets the background CO2 concentration. Only needed for the A-gs model.\\
 +Remark: If other sources in the model are of the CO2 type, they will add up to the CO2 concentration.