Passive microwave and optical index approaches for estimating surface conductance and evapotranspiration in forest ecosystems

In this study, we evaluated and compared optical and passive microwave index based retrievals of surface conductance (Gs) and evapotranspiration (ET) following the Penman-Monteith (PM) approach. The methodology was evaluated over the growing season at five FLUXNET sites in the USA and Australia enco...

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Detalles Bibliográficos
Publicado: 2015
Materias:
evapotranspiration
microwave index
optical indices
surface conductance
AMSR-E
comparative study
estimation method
forest ecosystem
hydraulic conductivity
index method
microwave radiation
model test
MODIS
parameterization
Penman-Monteith equation
performance assessment
vegetation type
Australia
United States
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01681923_v213_n_p126_Barraza
http://hdl.handle.net/20.500.12110/paper_01681923_v213_n_p126_Barraza
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paper:paper_01681923_v213_n_p126_Barraza
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spelling paper:paper_01681923_v213_n_p126_Barraza2023-06-08T15:17:43Z Passive microwave and optical index approaches for estimating surface conductance and evapotranspiration in forest ecosystems evapotranspiration microwave index optical indices surface conductance AMSR-E comparative study estimation method evapotranspiration forest ecosystem hydraulic conductivity index method microwave radiation model test MODIS parameterization Penman-Monteith equation performance assessment vegetation type Australia United States In this study, we evaluated and compared optical and passive microwave index based retrievals of surface conductance (Gs) and evapotranspiration (ET) following the Penman-Monteith (PM) approach. The methodology was evaluated over the growing season at five FLUXNET sites in the USA and Australia encompassing three forest types, deciduous broadleaf forest (DBF), evergreen needleleaf forest (ENF) and evergreen broadleaf forest (EBF). A subset of Gs values were regressed against individual and combined indices of NDWI, EVI, and FI (microwave frequency index), and used to parameterize the PM equation for retrievals of ET (PM-Gs). For this purpose, we used MODIS (MYD09A1) and AMSR-E passive microwave data to compute the VIs. Model performance was quantitatively evaluated through comparative analysis of the regression coefficients (r2), and root mean square errors (RMSE). All indices correlated well with Gs over deciduous broadleaf forests, explaining 40-60% of Gs variations, however, the optical-based models had lower RMSE than the microwave FI model. In contrast, the FI model yielded the best performance to estimate Gs in evergreen forests (EBF and ENF). Overall, a combined microwave-optical model resulted in the best Gs estimates in these evergreen forests compared with the individual model approaches. In general, the PM-models explained more than 70% of the variance in LE with RMSE lower than 20W/m2. Based on these results, we developed a new approach combining optical and passive microwave indices based on their spatial vs. temporal synergies to generate Gs time series. This combined optical-microwave approach produced the best ET estimates for evergreen forest and offered a robust approach for deciduous forest without sacrificing precision. © 2015 Elsevier B.V. 2015 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01681923_v213_n_p126_Barraza http://hdl.handle.net/20.500.12110/paper_01681923_v213_n_p126_Barraza
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic evapotranspiration
microwave index
optical indices
surface conductance
AMSR-E
comparative study
estimation method
evapotranspiration
forest ecosystem
hydraulic conductivity
index method
microwave radiation
model test
MODIS
parameterization
Penman-Monteith equation
performance assessment
vegetation type
Australia
United States
spellingShingle evapotranspiration
microwave index
optical indices
surface conductance
AMSR-E
comparative study
estimation method
evapotranspiration
forest ecosystem
hydraulic conductivity
index method
microwave radiation
model test
MODIS
parameterization
Penman-Monteith equation
performance assessment
vegetation type
Australia
United States
Passive microwave and optical index approaches for estimating surface conductance and evapotranspiration in forest ecosystems
topic_facet evapotranspiration
microwave index
optical indices
surface conductance
AMSR-E
comparative study
estimation method
evapotranspiration
forest ecosystem
hydraulic conductivity
index method
microwave radiation
model test
MODIS
parameterization
Penman-Monteith equation
performance assessment
vegetation type
Australia
United States
description In this study, we evaluated and compared optical and passive microwave index based retrievals of surface conductance (Gs) and evapotranspiration (ET) following the Penman-Monteith (PM) approach. The methodology was evaluated over the growing season at five FLUXNET sites in the USA and Australia encompassing three forest types, deciduous broadleaf forest (DBF), evergreen needleleaf forest (ENF) and evergreen broadleaf forest (EBF). A subset of Gs values were regressed against individual and combined indices of NDWI, EVI, and FI (microwave frequency index), and used to parameterize the PM equation for retrievals of ET (PM-Gs). For this purpose, we used MODIS (MYD09A1) and AMSR-E passive microwave data to compute the VIs. Model performance was quantitatively evaluated through comparative analysis of the regression coefficients (r2), and root mean square errors (RMSE). All indices correlated well with Gs over deciduous broadleaf forests, explaining 40-60% of Gs variations, however, the optical-based models had lower RMSE than the microwave FI model. In contrast, the FI model yielded the best performance to estimate Gs in evergreen forests (EBF and ENF). Overall, a combined microwave-optical model resulted in the best Gs estimates in these evergreen forests compared with the individual model approaches. In general, the PM-models explained more than 70% of the variance in LE with RMSE lower than 20W/m2. Based on these results, we developed a new approach combining optical and passive microwave indices based on their spatial vs. temporal synergies to generate Gs time series. This combined optical-microwave approach produced the best ET estimates for evergreen forest and offered a robust approach for deciduous forest without sacrificing precision. © 2015 Elsevier B.V.
title Passive microwave and optical index approaches for estimating surface conductance and evapotranspiration in forest ecosystems
title_short Passive microwave and optical index approaches for estimating surface conductance and evapotranspiration in forest ecosystems
title_full Passive microwave and optical index approaches for estimating surface conductance and evapotranspiration in forest ecosystems
title_fullStr Passive microwave and optical index approaches for estimating surface conductance and evapotranspiration in forest ecosystems
title_full_unstemmed Passive microwave and optical index approaches for estimating surface conductance and evapotranspiration in forest ecosystems
title_sort passive microwave and optical index approaches for estimating surface conductance and evapotranspiration in forest ecosystems
publishDate 2015
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01681923_v213_n_p126_Barraza
http://hdl.handle.net/20.500.12110/paper_01681923_v213_n_p126_Barraza
_version_ 1768542688545603584

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