FVI-A Floating Vegetation Index Formed with Three Near-IR Channels in the 1.0-1.24 uM Spectral Range for the Detection of Vegetation Floating over Water Surfaces
Journal Article - Open Access
NAVAL RESEARCH LAB WASHINGTON DC WASHINGTON United States
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Through the analysis of hyperspectral imaging data collected over water surfaces covered by floating vegetation, such as Sargassum and algae, we observed that the spectra commonly contain a reflectance peak centered near 1.07 mu m. This peak results from the competing effects between the well-known vegetation reflectance plateau in the 0.81-1.3 mu m spectral range and the absorption effects above 0.75 mu m by liquid water within the vegetation and in the surrounding water bodies. In this article, we propose a new index, namely the floating vegetation index FVI, for the hyperspectral remote sensing of vegetation over surface layers of oceans and inland lakes. In the formulation of the FVI, one channel centered near 1.0 mu m and another 1.24 mu m are used to form a linear baseline. The reflectance value of the third channel centered at the 1.07-mu m reflectance peak above the baseline is defined as the FYI. Hyperspectral imaging data acquired with the AVIRIS Airborne Visible Infrared Imaging Spectrometer instrument over the Gulf of Mexico and over salt ponds near Moffett Field in southern portions of the San Francisco Bay were used to demonstrate the success in detecting Sargassum and floating algae with this index. It is expected that the use of this index for the global detection of floating vegetation from hyperspectral imaging data to be acquired with future satellite sensors will result in improved detection and therefore enhanced capability in estimating primary production, a measure of how much carbon is fixed per unit area per day by oceans and inland lakes.
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