Atmospherically Resistant Vegetation Index (ARVI) for EOS-MODIS

Abstract

Atmospherically resistant vegetation index (ARVI) is proposed and developed to be used for remote sensing of vegetation from the Earth Observing System (EOS) MODIS sensor. The same index can be used for remote sensing from Landsat TM, and the EOS-HIRIS sensor. The index takes advantage of the presence of the blue channel (0.47±0.01 μm) in the MODIS sensor, in addition to the red (0.66±0.025 μm) and the near IR (0.865±0.02 μm) channels that compose the present normalized difference vegetation index (NDVI). The resistance of the ARVI to atmospheric effects (in comparison to the NDVI) is accomplished by a self-correction process for the atmospheric effect on the red channel, using the difference in the radiance between the blue and the red channels to correct the radiance in the red channel. Simulations using radiative transfer computations on arithmetic and natural surface spectra, for various atmospheric conditions, show that ARVI has a similar dynamic range to the NDVI, but is, on average, four times less sensitive to atmospheric effects than the NDVI. The improvement is much better for vegetated surfaces than for soils. It is much better for moderate to small size aerosol particles (e.g., continental, urban, or smoke aerosol) than for large particle size (e.g., maritime aerosol or dust). Due to a fortunate coincidence, the same optimal value of the parameter that defines the weighting of the blue band radiance in the ARVI definition, is found for vegetated areas with small to moderate aerosol particle size (e.g., anthropogenic aerosol and smoke) and for arid regions with large particle size (e.g., dust). Therefore, a single combination of the blue and the red channels in the ARVI may be used in all or most remote sensing applications. Due to the excellent atmospheric resistance of the ARVI, it is expected that remote sensing from MODIS of the vegetation index over most land surfaces will include molecular and ozone correction with no further need for aerosol correction, except for dust conditions, like in the Sahel. © 1992 IEEE