Sensitivity Analysis of TSEB Model by One-Factor-At-A-Time in irrigated olive orchard
The aim objective of this present study is to identify the most influencing constant parameters of Two Source Energy Balance (TSEB) Model over irrigated olive orchard in semi-arid area. TSEB (Norman et al. 1995) has been based on surface radiometric temperature, Priestley-Taylor estimation of canopy latent heat, climatic forcing and partitioning energy to double sources (canopy and soil) according parallel resistances network. Sensitivity analysis by approach One-Factor-At-A-Time (OAT) was been studied using Eddy Covariance ground measurements data collected during SUDMED Project in Agdal site, Marrakech, Morocco (2003). Data include surface energy fluxes, meteorological inputs and vegetation parameters related to olive orchard. OAT consists in modifying each input parameters of the model by ±10% around its initial value. The effect of each operated modification is analyzed on four outputs of the model (i.e: Net radiation, latent heat, sensible heat and soil heat), using variation rate and sensitivity index. The input parameters data such as Leaf Area Index (LAI), Priestley-Taylor constant (αp), and fraction of LAI that is green (fg) have successively a percentage variation of 18.4%, 15.1%, and 15.1% shown to have the greatest impact on the TSEB estimate of the fluxes.
Thus, the results obtained give a fairly clear idea of the most important entrances of TSEB. They can guide the user through the calibration process and also in collecting experimental data.
Keywords: TSEB Model, Sensitivity analysis, One-Factor-At-A-Time, Sensitivity index, percentage of variation
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