Monitoring Vegetation Moisture Using Passive Microwave and Optical Indices in the Dry Chaco Forest, Argentina

Barraza, Verónica Guadalupe Jiménez; Grings, F.; Ferrazzoli, P.; Salvia, M.; Maas, Martín; Rahmoune, R.; Vittucci, Cristina; Karszenbaum, H.

doi:10.1109/jstars.2013.2268011

Cited by 13 publications

(11 citation statements)

References 55 publications

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“…Nevertheless, our results also agree with the literature [Prigent et al, 1999;Min and Lin, 2006;Li et al, 2009;Jones et al, 2012;Barraza et al, 2014], showing that the FI versus PI relation provides a sound physical-biophysical scheme to characterize main hydrological dynamics of the ecosystem. Using this scheme, it can be seen that the methodologies developed by Min and Lin [2006] or Barraza et al [2014] can only be applied for densely vegetated area, in which the key hypothesis required for the methodology is met. Moreover, although for these ecosystems the key processes which relate ET to microwave indices will be the same (decrease of vegetation moisture, decrease of ET, and increase of FI), the relation will be a function of the values of geometrical and dielectric characteristics of the canopy and, in general, will vary for different ecosystems.…”

Section: Discussionsupporting

confidence: 91%

“…To better interpret the microwave data, we used prior analyses made over Dry Chaco Forest [Barraza et al, 2014] as a benchmark case. Seasonal trends over this area were previously explained by Barraza et al [2014] using a theoretical emission model accounting for changes in both LAI and vegetation moisture.…”

Section: Discussionmentioning

confidence: 99%

“…Seasonal trends over this area were previously explained by Barraza et al [2014] using a theoretical emission model accounting for changes in both LAI and vegetation moisture. MODIS LAI largely accounted for changes in FI seasonal trends (phenology), and short-term changes in FI were associated with vegetation moisture effects (e.g., hydric stress) [Barraza et al, 2014]. In this analysis, the observed inverse relation between MODIS EVI and FI was explained on the basis of the above-mentioned moisture-vegetation relationship.…”

Section: Discussionmentioning

confidence: 99%

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Behavior of multitemporal and multisensor passive microwave indices in Southern Hemisphere ecosystems

et al. 2014

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This study focused on the time series analysis of passive microwave and optical satellite data collected from six Southern Hemisphere ecosystems in Australia and Argentina. The selected ecosystems represent a wide range of land cover types, including deciduous open forest, temperate forest, tropical and semiarid savannas, and grasslands. We used two microwave indices, the frequency index (FI) and polarization index (PI), to assess the relative contributions of soil and vegetation properties (moisture and structure) to the observations. Optical-based satellite vegetation products from the Moderate Resolution Imaging Spectroradiometer were also included to aid in the analysis. We studied the X and Ka bands of the Advanced Microwave Scanning Radiometer-EOS and Wind Satellite, resulting in up to four observations per day (1:30, 6:00, 13:30, and 18:00 h). Both the seasonal and hourly variations of each of the indices were examined. Environmental drivers (precipitation and temperature) and eddy covariance measurements (gross ecosystem productivity and latent energy) were also analyzed. It was found that in moderately dense forests, FI was dependent on canopy properties (leaf area index and vegetation moisture). In tropical woody savannas, a significant regression (R 2 ) was found between FI and PI with precipitation (R 2 > 0.5) and soil moisture (R 2 > 0.6). In the areas of semiarid savanna and grassland ecosystems, FI variations found to be significantly related to soil moisture (R 2 > 0.7) and evapotranspiration (R 2 > 0.5), while PI varied with vegetation phenology. Significant differences (p < 0.01) were found among FI values calculated at the four local times.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Behavior of multitemporal and multisensor passive microwave indices in Southern Hemisphere ecosystems

et al. 2014

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“…The performance of moisture indexes (computed from NIR and SWIR) was comparable (R 2 from 0.65 to 0.76), whereas for biomass vegetation indexes, MSAVI and ANDVI performed better than NDVI, EVI and SAVI (R 2 from 0.43 to 0.73). We particularly demonstrated and quantified the effect of LAI on retrieving EWTCAN mentioned in [16,24,27] for regional-scale drought assessment under a tree cover/LAI gradient from dense to open forest. LAI adaptive inversion models for retrieving EWTCAN are then proposed for Mediterranean forests drought monitoring by the VI/LAI inversion model for moderately-covered areas and the VI inversion model for denser forests.…”

Section: Discussionmentioning

confidence: 99%

“…Empirical methods compare field measurements of vegetation water content to MVI and BVI computed from multi-temporal satellite images, whereas physical models, known as radiative transfer models (RTM), use rather simulated reflectances or hyper spectral data. Optical remote sensing was also combined in other studies with passive microwave observations known to better succeed in canopy water content, integrating the contribution of trunk and branch water content (e.g., [24]). …”

Section: Introductionmentioning

confidence: 99%

Regional Equivalent Water Thickness Modeling from Remote Sensing across a Tree Cover/LAI Gradient in Mediterranean Forests of Northern Tunisia

2015

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Abstract:The performance of vegetation indexes derived from moderate resolution imaging spectroradiometer (MODIS) sensors is explored for drought monitoring in the forests of Northern Tunisia; representing a transition zone between the Mediterranean Sea and the Sahara Desert. We investigated the suitability of biomass and moisture vegetation indexes for vegetation water content expressed by the equivalent water thickness (EWT) in a Mediterranean forest ecosystem with contrasted water budgets and desiccation rates. We proposed a revised EWT at canopy level (EWTCAN) based on weekly field measurements of fuel moisture in seven species during the 2010 dry period, considering the mixture of plant functional types for water use (trees, shrubs and herbaceous layers) and a varying vegetation cover. MODIS vegetation indexes computed and smoothed over the dry season were highly correlated with the EWTCAN. The performances of moisture indexes Normalized Difference Infrared Index (NDII6 and NDII7) and Global Moisture Vegetation Index (GVMI6 and GVMI7) were comparable, whereas for biomass vegetation indexes, Normalized Difference 1938Vegetation Index (NDVI), Modified Soil Adjusted Vegetation Index (MSAVI) and Adjusted Normalized Difference Vegetation Index (ANDVI) performed better than Enhanced Vegetation Index (EVI) and Soil Adjusted Vegetation Index (SAVI). We also identified the effect of Leaf Area Index (LAI) on EWTCAN monitoring at the regional scale under the tree cover/LAI gradient of the region from relatively dense to open forest. Statistical analysis revealed a significant decreasing linear relationship; indicating that for LAI less than two, the greater the LAI, the less responsive are the vegetation indexes to changes in EWTCAN; whereas for higher LAI, its influence becomes less significant and was not considered in the inversion models based on vegetation indexes. The EWTCAN time-course from LAI-adapted inversion models based on significantly-related vegetation indexes to EWTCAN showed close profiles resulting from the inversion models using NDVI, ANDVI, MSAVI and NDII6 applied during the dry season. The developed EWTCAN model from MODIS vegetation indexes for the study region was finally tested for its ability to capture the topo-climatic effects on the seasonal and the spatial patterns of desiccation/rewetting for keystone periods of Mediterranean vegetation functioning. Implications for further use in scientific developments or management are discussed.

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

Barraza

Restrepo‐Coupe

Huete

et al. 2015

Agricultural and Forest Meteorology

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Monitoring Vegetation Moisture Using Passive Microwave and Optical Indices in the Dry Chaco Forest, Argentina

Cited by 13 publications

References 55 publications

Behavior of multitemporal and multisensor passive microwave indices in Southern Hemisphere ecosystems

Behavior of multitemporal and multisensor passive microwave indices in Southern Hemisphere ecosystems

Regional Equivalent Water Thickness Modeling from Remote Sensing across a Tree Cover/LAI Gradient in Mediterranean Forests of Northern Tunisia

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

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