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AUTHOR(S): Asmae Zbiri, Dominique Haesen, Fatima Ezzahrae El Alaoui-Faris, Azeddine Hachmi, David A. Vaccari
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ABSTRACT We studied the effectiveness of FAPAR and DMP data at regional scale. In this article, we propose theoretical algorithms for calibration of these data in a larger scale (for all Moroccan rangelands). The study uses Multivariate Polynomial Regression (MPR) via TaylorFit software. The relationship between soil moisture SWI from MetOp-A / ASCAT sensor, fraction of photosynthetically active absorbed radiation absorbed (FAPAR) and dry matter productivity (DMP) from SPOT / VEGETATION and PROBA-V was set at 11 km resolution for ten years. Three types of areas were studied: degraded areas, sparse herbaceous and shrub vegetation. The calibration of phenological indices is made with two hypothesis (areas with low values are divided by 3000 and areas with high values are divided by 100). Multivariate Polynomial Regression (MPR) with TaylorFit expresses clearly errors of current and corrected estimates of FAPAR, DMP and Normalized difference vegetation index (NDVI) data respectively (from Max Err = 116.94 / RMSE = 48.47 to Max Err = 0.04 / RMSE = 0.016) and (hypothesis 2: from Max Err = 30.4 / RMSE = 9.59 to Max Err = 0.30 / RMSE = 0.09). Similarly, in order to compare and verify these results according to field data, a comparison was made over two years. The similarity of FAPAR and DMP data and phytomass measurements is strongly expressed. A significant polynomial correlation is estimated between SWI, dry matter productivity and photosynthetic fraction respectively (Rsq = 0.90) and (Rsq = 0.87). The provision of infor-mation on quality and validation of FAPAR and DMP indices facilitates their use in monitoring drought in these areas. |
KEYWORDS Absorbed photosynthetically active radiation fraction (FAPAR), Dry matter productivity (DMP), Normalized difference vegetation index (NDVI), Soil moisture index (SWI), Moroccan rangelands, Multivariate Polynomial Regression, phytomass measurements, Calibration algorithm. |
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Cite this paper Asmae Zbiri, Dominique Haesen, Fatima Ezzahrae El Alaoui-Faris, Azeddine Hachmi, David A. Vaccari. (2021) Algorithm Theoretical for FAPAR and DMP Calibration Using Remote Sensing and Field Data in Moroccan Arid Areas. International Journal of Environmental Science, 6, 11-22 |
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