Improving the performance of 3-D radiative transfer model FLIGHT to simulate optical properties of a tree-grass ecosystem

Melendo-Vega, J.R. ; Martín, M.P. ; Pacheco-Labrador, J. ; González-Cascón, R. ; Moreno, G. ; Pérez, F. (Universidad de Zaragoza) ; Migliavacca, M. ; García, M. ; North, P. ; Riaño, D.

Resumen: The 3-D Radiative Transfer Model (RTM) FLIGHT can represent scattering in open forest or savannas featuring underlying bare soils. However, FLIGHT might not be suitable for multilayered tree-grass ecosystems (TGE), where a grass understory can dominate the reflectance factor (RF) dynamics due to strong seasonal variability and low tree fractional cover. To address this issue, we coupled FLIGHT with the 1-D RTM PROSAIL. The model is evaluated against spectral observations of proximal and remote sensing sensors: the ASD Fieldspec® 3 spectroradiometer, the Airborne Spectrographic Imager (CASI) and the MultiSpectral Instrument (MSI) onboard Sentinel- 2. We tested the capability of both PROSAIL and PROSAIL+FLIGHT to reproduce the variability of different phenological stages determined by 16-year time series analysis of Moderate Resolution Imaging Spectroradiometer-Normalized Difference Vegetation Index (MODIS-NDVI). Then, we combined concomitant observations of biophysical variables and RF to test the capability of the models to reproduce observed RF. PROSAIL achieved a Relative Root Mean Square Error (RRMSE) between 6% to 32% at proximal sensing scale. PROSAIL+FLIGHT RRMSE ranged between 7% to 31% at remote sensing scales. RRMSE increased in periods when large fractions of standing dead material mixed with emergent green grasses -especially in autumn-; suggesting that the model cannot represent the spectral features of this material. PROSAIL+FLIGHT improves RF simulation especially in summer and at mid-high view angles.

Idioma: Inglés

DOI: 10.3390/rs10122061

Año: 2018

Publicado en: Remote Sensing 10, 12 (2018), 2061 [33 pp]
ISSN: 2072-4292

Factor impacto JCR: 4.118 (2018)

Categ. JCR: REMOTE SENSING rank: 7 / 30 = 0.233 (2018) - Q1 - T1

Factor impacto SCIMAGO: 1.43 - Earth and Planetary Sciences (miscellaneous) (Q1)

Financiación: info:eu-repo/grantAgreement/ES/MEC/FPU15-03558
Financiación: info:eu-repo/grantAgreement/ES/MINECO/CGL2012-34383
Financiación: info:eu-repo/grantAgreement/ES/MINECO/CGL2015-G9095-R

Tipo y forma: Article (Published version)

Área (Departamento): Área Análisis Geográfico Regi. (Dpto. Geograf. Ordenac.Territ.)