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| Titel |
Comparison of four models to calculate canopy resistance of maize in North Italy |
| VerfasserIn |
O. Gharsallah, G. Ravazzani, M. Mancini, G. Rana |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250040388
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| Zusammenfassung |
| This paper examines four models for estimating canopy resistance rc, since it is not a purely
physiological term, but it depends also on the prevailing climatic conditions get established
over the canopy, in order to calculate the actual evapotranspiration on hourly and daily scales,
for maize crop grown in North Italy. A comparison between Measured and estimated eddy
covariance data was carried out by analysing in details the four models 1) Monteith, 2) Jarvis,
3) Katerji-Perrier, 4) Todorovic. They are either semi-empirical (1, 2 and 3) or mechanistic
(4). Furthermore, the FAO approach was also evaluated and compared with the others
techniques.
In synthesis, rc has not been considered as constant but modelled in function
of leaf area index through the approach of Monteith and influenced by the photo
synthetically active radiation, the vapour pressure deficit, ambient temperature and the
soil moisture through the approach of Jarvis. Moreover, rc has been modelled as a
function of the climatic variables and water status condition through the approach
of Katerji-Perrier which needs a calibration and finally as a function of only the
climatic condition through the approach of Todorovic which does not need any
calibration.
The results confirmed the good accuracy of Katerji-Perrier method at both hourly
and daily scale, while the approach of Monteith, Jarvis and Todorovic provided an
overestimation respectively 12%, 27% and 30%. However, the evaluation of FAO
method gave an overestimation and showed that both ET0 and Kc could be sources of
errors.
Key words: Canopy resistance, eddy covariance, Monteith, Jarvis, Katerji-Perrier,
Todorovic, FAO |
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