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| DOI | 10.1016/J.RSE.2014.02.011 | ||||
| Año | 2014 | ||||
| Tipo | artículo de investigación |
Citas Totales
Autores Afiliación Chile
Instituciones Chile
% Participación
Internacional
Autores
Afiliación Extranjera
Instituciones
Extranjeras
Surface albedo and emissivity are essential variables in surface energy balance. In recent decades, several land surface energy models have used both surface broadband albedo and emissivity in order to achieve reliable evapotranspiration retrievals on a daily basis. Despite these improvements in surface energy models, we noticed an assumption that most studies make when using this framework. It assumes that the surface broadband albedo and emissivity can be estimated directly as a weighted average of spectral surface bi-directional reflectances, and as a weighted average of spectral surface emissivities retrieved at a given view angle, respectively. However, this approach does not take into account surface anisotropy, which is described by the Bi-directional Reflectance Distribution Function (BRDF) in the case of the surface albedo. In this paper, we analyze the influence that estimating land surface albedo directly from the surface reflectance (alpha(REF)) or through the BRDF integration (alpha(BRDF)) has on the estimation of energy balance components (net radiation, latent and sensible heat fluxes and evapotranspiration) by using the Simplified Surface Energy Balance Index (S-SEBI). To this end, in-situ data and remote sensing images acquisitioned at different view zenith angles (VZA) such as 0 degrees, +/- 40 degrees and +/- 57 degrees by the Airborne Hyperspectral Scanner (AHS) over an agricultural area were used. Results show high variation in alpha(REF) depending on the VZA when compared to alpha(BRDF), with the highest difference observed in the backward scattering direction along the hot spot region (RMSE of 0.11 and relative error of 65%). Net radiation gives relative errors from 6 to 17%, with the maximum error obtained in the images that include the hot spot effect, whereas significant changes are not observed in case of the ground heat flux and the evaporative fraction. However, sensible heat flux, latent heat flux and daily evapotranspiration show relative errors ranging between 23-39%, 6-18% and 5-15% respectively. In a future study, the influence of estimating surface emissivity directly from the average of spectral emissivities under a given view angle or using a hemispherical value will be analyzed. (C) 2014 Elsevier Inc. All rights reserved.
| Ord. | Autor | Género | Institución - País |
|---|---|---|---|
| 1 | MATTAR-BADER, CRISTIAN | Hombre |
Univ Valencia - España
Universidad de Chile - Chile University of Valencia - España Universitat de València - España |
| 2 | Franch, B. | - |
UNIV MARYLAND - Estados Unidos
NASA - Estados Unidos University of Maryland - Estados Unidos NASA Goddard Space Flight Center - Estados Unidos University of Maryland, College Park - Estados Unidos |
| 3 | Sobrino, Jose A. | Hombre |
Univ Valencia - España
University of Valencia - España Universitat de València - España |
| 4 | Corbari, C. | - |
Politecn Milan - Italia
Politecnico di Milano - Italia |
| 5 | Jimenez, Juan C. | Hombre |
Univ Valencia - España
University of Valencia - España Universitat de València - España |
| 6 | Olivera-Guerra, Luis E. | Hombre |
Universidad de Chile - Chile
|
| 7 | Skokovic, D. | - |
Univ Valencia - España
University of Valencia - España Universitat de València - España |
| 8 | Soria, Guillem | Hombre |
Univ Valencia - España
University of Valencia - España Universitat de València - España |
| 9 | Oltra-Carrio, R. | - |
Univ Valencia - España
University of Valencia - España Universitat de València - España |
| 10 | Julien, Yves | Hombre |
Univ Valencia - España
University of Valencia - España Universitat de València - España |
| 11 | Mancini, M. | - |
Politecn Milan - Italia
Politecnico di Milano - Italia |
| Fuente |
|---|
| Ministerio de Economía y Competitividad |
| Comisión Nacional de Investigación Científica y Tecnológica |
| European Commission |
| Comisión Nacional de Investigación CientÃfica y Tecnológica |
| Ministerio de EconomÃa y Competitividad |
| Program U-INICIA VID |
| CEOS-Spain |
| Ministerio de Economia y Competitividad (EODIX) |
| European Union (CEOP-AEGIS) |
| Fondecyt-Initial |
| EODIX |
| CEOP-AEGIS |
| Santander Fellowship-University of Chile for young scientist |
| Agradecimiento |
|---|
| We acknowledge funding from the European Union (CEOP-AEGIS, project FP7-ENV-2007-1 Proposal No. 212921) and the Ministerio de Economia y Competitividad (EODIX, project AYA2008-0595-C04-01; CEOS-Spain, project AYA2011-29334-C02-01. This work was also partially funded by Program U-INICIA VID 2012, grant U-INICIA 4/0612; Santander Fellowship-University of Chile for young scientist and Fondecyt-Initial (CONICYT/ref-11130359). |
| We acknowledge funding from the European Union (CEOP-AEGIS , project FP7-ENV-2007-1 Proposal No. 212921 ) and the Ministerio de Economía y Competitividad (EODIX , project AYA2008-0595-C04-01 ; CEOS-Spain , project AYA2011-29334-C02-01 . This work was also partially funded by Program U-INICIA VID 2012 , grant U-INICIA 4/0612 ; Santander Fellowship—University of Chile for young scientist and Fondecyt-Initial (CONICYT /ref- 11130359 ). |