A Measurement Based Sensitivity Analysis of the Penman-Monteith Actual Evapotranspiration Model for Crops of Different Height and in Contrasting Water Status |
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| Authors: | G Rana N Katerji |
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| Institution: | (1) Research Physicist, Istituto Sperimentale Agronomico, Bari, Italy, IT;(2) Research Ecophysiologist, INRA-Unité de Bioclimatologie, Thiverval-Gignon, France, FR |
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| Abstract: | Summary This paper presents a study of the sensibility of the Penman-Monteith evapotranspiration model to climatic (available energy
and vapour pressure deficit) and parametric (aerodynamic and canopy resistances, r
a
and r
c
respectively) factors in a semi-arid climate, for crops in contrasting water status (well irrigated and under water stress)
and of different heights. Three experiments were carried out in southern Italy on reference grass (≈ 0.1 m), grain sorghum
(≈ 1 m) and sweet sorghum (≈ 3 m). For this analysis the sensitivity coefficients, taken as hourly means, were evaluated during
the growth season when the crops completely covered the soil. The relative errors on evapotranspiration were also evaluated
for r
a
and r
c
. The results showed that, for reference grass, available energy and aerodynamic resistance play a major role. For crops under
water stress the most important term to evaluate is canopy resistance. For a tall crop, as sweet sorghum, the role of the
vapour pressure deficit is fundamental, both when the crop is in good water status and under water stress.
Received July 14, 1997 Revised February 5, 1998 |
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| Keywords: | |
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