Narrowband Greenness

Narrowband greenness VIs are combinations of reflectance measurements sensitive to the combined effects of foliage chlorophyll concentration, canopy leaf area, foliage clumping, and canopy architecture. Similar to the broadband greenness VIs, narrowband greenness VIs are designed to provide a measure of the overall amount and quality of photosynthetic material in vegetation, which is essential for understanding the state of vegetation. Narrowband greenness VIs are intended for use with imaging spectrometers.

One area where narrowband greenness VIs are useful is precision agriculture. This is an information- and technology-based agricultural management system to identify, analyze, and manage site-soil spatial and temporal variability.

Most of these VIs use reflectance measurements in the red and near-infrared regions to sample the red edge portion of the reflectance curve. The red edge is a name used to describe the steeply sloped region of the vegetation reflectance curve between 690 nm and 740 nm that is caused by the transition from chlorophyll absorption and near-infrared leaf scattering. Use of near-infrared measurements, with much greater penetration depth through the canopy than red measurements, allows estimation of the total amount of green material in the column.

Making narrowband measurements in the red edge allows these indices to be more sensitive to smaller changes in vegetation health than the broadband greenness VIs, particularly in conditions of dense vegetation where the broadband measures can saturate.

ENVI provides the following narrowband greenness VIs:

Atmospherically Resistant Vegetation Index (ARVI)

This index was originally designed for use with MODIS. It is an enhancement to the NDVI that is relatively resistant to atmospheric factors (for example, aerosol). It uses blue reflectance to correct red reflectance for atmospheric scattering. It is most useful in regions of high atmospheric aerosol content, including tropical regions contaminated by soot from slash-and-burn agriculture.

The gamma constant is a weighting function that depends on aerosol type. ENVI uses a value of 1 for gamma. You should correct the imagery for atmospheric effects (including aerosols) prior to computing this index.

The value of this index ranges from -1 to 1, with higher pixel values corresponding to healthier and greener vegetation.

See Narrowband Definitions for the allowable range of wavelengths.

Reference: Kaufman, Y., and D. Tanre. "Atmospherically Resistant Vegetation Index (ARVI) for EOS-MODIS. IEEE Transactions on Geoscience and Remote Sensing 30, no. 2 (1992): 261-270.

Modified Chlorophyll Absorption Ratio Index (MCARI)

This index is one of several CARI indices that indicates the relative abundance of chlorophyll. Daughtry et al. (2000) simplified the CARI index to minimize the combined effects of soil and non-photosynthetic surfaces.

See Narrowband Definitions for the allowable range of wavelengths.

Reference: Daughtry, C., et al. "Estimating Corn Leaf Chlorophyll Concentration from Leaf and Canopy Reflectance." Remote Sensing Environment 74 (2000): 229–239.

Modified Chlorophyll Absorption Ratio Index Improved (MCARI2)

This index is similar to MCARI but is considered a better predictor of green leaf area index (LAI). It incorporates a soil adjustment factor while preserving sensitivity to LAI and resistance to chlorophyll influence.

See Narrowband Definitions for the allowable range of wavelengths.

Reference: Haboudane, D., et al. "Hyperspectral Vegetation Indices and Novel Algorithms for Predicting Green LAI of Crop Canopies: Modeling and Validation in the Context of Precision Agriculture." Remote Sensing of Environment 90 (2004): 337-352.

Modified Red Edge Normalized Difference Vegetation Index (MRENDVI)

This index is a modification of the Red Edge NDVI that corrects for leaf specular reflection. It capitalizes on the sensitivity of the vegetation red edge to small changes in canopy foliage content, gap fraction, and senescence. Applications include precision agriculture, forest monitoring, and vegetation stress detection.

The value of this index ranges from -1 to 1. The common range for green vegetation is 0.2 to 0.7. See Narrowband Definitions for the allowable range of wavelengths.

References:

Datt, B. "A New Reflectance Index for Remote Sensing of Chlorophyll Content in Higher Plants: Tests Using Eucalyptus Leaves." Journal of Plant Physiology 154 (1999): 30-36.

Sims, D. and J. Gamon. "Relationships Between Leaf Pigment Content and Spectral Reflectance Across a Wide Range of Species, Leaf Structures and Developmental Stages." Remote Sensing of Environment 81 (2002): 337-354.

Modified Red Edge Simple Ratio (MRESR)

This index is a modification of the broadband simple ratio (SR). It uses bands in the red edge and incorporates a correction for leaf specular reflection. Applications include precision agriculture, forest monitoring, and vegetation stress detection.

The value of this index ranges from 0 to 30. The common range for green vegetation is 2 to 8. See Narrowband Definitions for the allowable range of wavelengths.

References:

Sims, D., and J. Gamon. "Relationships Between Leaf Pigment Content and Spectral Reflectance Across a Wide Range of Species, Leaf Structures and Developmental Stages." Remote Sensing of Environment 81 (2002):337-354.

Datt, B. "A New Reflectance Index for Remote Sensing of Chlorophyll Content in Higher Plants: Tests Using Eucalyptus Leaves." Journal of Plant Physiology 154 (1999):30-36.

Modified Triangular Vegetation Index (MTVI)

This index makes TVI suitable for LAI estimations by replacing the 750 nm wavelength with 800 nm, whose reflectance is influenced by changes in leaf and canopy structures.

See Narrowband Definitions for the allowable range of wavelengths.

Reference: Haboudane, D., et al. "Hyperspectral Vegetation Indices and Novel Algorithms for Predicting Green LAI of Crop Canopies: Modeling and Validation in the Context of Precision Agriculture." Remote Sensing of Environment 90 (2004): 337-352.

Modified Triangular Vegetation Index - Improved (MTVI2)

This index is similar to MTVI but is considered a better predictor of green LAI. It accounts for the background signature of soils while preserving sensitivity to LAI and resistance to the influence of chlorophyll.

See Narrowband Definitions for the allowable range of wavelengths.

Reference: Haboudane, D., et al. "Hyperspectral Vegetation Indices and Novel Algorithms for Predicting Green LAI of Crop Canopies: Modeling and Validation in the Context of Precision Agriculture." Remote Sensing of Environment 90 (2004): 337-352.

Red Edge Normalized Difference Vegetation Index (RENDVI)

This index is a modification of the traditional broadband NDVI. Applications include precision agriculture, forest monitoring, and vegetation stress detection. This VI differs from the NDVI by using bands along the red edge, instead of the main absorption and reflectance peaks. It capitalizes on the sensitivity of the vegetation red edge to small changes in canopy foliage content, gap fraction, and senescence.

The value of this index ranges from -1 to 1. The common range for green vegetation is 0.2 to 0.9. See Narrowband Definitions for the allowable range of wavelengths.

References:

Gitelson, A., and M. Merzlyak. "Spectral Reflectance Changes Associated with Autumn Senescence of Aesculus Hippocastanum L. and Acer Platanoides L. Leaves." Journal of Plant Physiology 143 (1994): 286‑292.

Sims, D., and J. Gamon. "Relationships Between Leaf Pigment Content and Spectral Reflectance Across a Wide Range of Species, Leaf Structures and Developmental Stages." Remote Sensing of Environment 81 (2002): 337-354.

Red Edge Position Index (REPI)

This index is a narrowband reflectance measurement that is sensitive to changes in chlorophyll concentration. Increased chlorophyll concentration broadens the absorption feature and moves the red edge to longer wavelengths.

Results are reported as the wavelength of the maximum derivative of reflectance in the vegetation red edge region of the spectrum in microns from 690 nm to 740 nm. The common range for green vegetation is 700 nm to 730 nm. Applications include crop monitoring and yield prediction, ecosystem disturbance detection, photosynthesis modeling, and canopy stress caused by climate and other factors.

See Narrowband Definitions for the allowable range of wavelengths.

Reference: Curran, P., W. Windham, and H. Gholz. "Exploring the Relationship Between Reflectance Red Edge and Chlorophyll Concentration in Slash Pine Leaves." Tree Physiology 15 (1995): 203-206.

Transformed Chlorophyll Absorption Reflectance Index (TCARI)

This index is one of several CARI indices that indicates the relative abundance of chlorophyll. It is affected by the underlying soil reflecance, particularly in vegetation with a low LAI.

See Narrowband Definitions for the allowable range of wavelengths.

Reference: Haboudane, D., et al. "Hyperspectral Vegetation Indices and Novel Algorithms for Predicting Green LAI of Crop Canopies: Modeling and Validation in the Context of Precision Agriculture." Remote Sensing of Environment 90 (2004): 337-352.

Triangular Vegetation Index (TVI)

This index is calculated as the area of a hypothetical triangle in spectral space that connects (1) green peak reflectance, (2) minimum chlorophyll absorption, and (3) the NIR shoulder. When chlorophyll absorption causes a decrease of red reflectance, and leaf tissue abundance causes an increase in NIR reflectance, the total area of the triangle increases. It is good for estimating green LAI, but its sensitivity to chlorophyll increases with an increase in canopy density.

See Narrowband Definitions for the allowable range of wavelengths.

Reference: Broge, N., and E. Leblanc. "Comparing Prediction Power and Stability of Broadband and Hyperspectral Vegetation Indices for Estimation of Green Leaf Area and Canopy Chlorophyll Density." Remote Sensing of Environment 76 (2000): 156-172.

Vogelmann Red Edge Index 1 (VREI1)

This index is a narrowband reflectance measurement that is sensitive to the combined effects of foliage chlorophyll concentration, canopy leaf area, and water content. Applications include vegetation phenology (growth) studies, precision agriculture, and vegetation productivity modeling.

The value of this index ranges from 0 to 20. The common range for green vegetation is 4 to 8. See Narrowband Definitions for the allowable range of wavelengths.

Reference: Vogelmann, J., B. Rock, and D. Moss. "Red Edge Spectral Measurements from Sugar Maple Leaves." International Journal of Remote Sensing 14 (1993): 1563-1575.

Vogelmann Red Edge Index 2 (VREI2)

This index is a narrowband reflectance measurement that is sensitive to the combined effects of foliage chlorophyll concentration, canopy leaf area, and water content. Applications include vegetation phenology (growth) studies, precision agriculture, and vegetation productivity modeling.

The value of this index ranges from 0 to 20. The common range for green vegetation is 4 to 8. See Narrowband Definitions for the allowable range of wavelengths.

Reference: Vogelmann, J., B. Rock, and D. Moss. "Red Edge Spectral Measurements from Sugar Maple Leaves." International Journal of Remote Sensing 14 (1993): 1563-1575.

See Also

Spectral Indices, Vegetation Indices, Vegetation Analysis Tools, Vegetation and Its Reflectance Properties, EO-1 Hyperion Vegetation Indices Tutorial