HR: 08:15h
AN: B11F-02 INVITED [Abstracts]
TI: Remote Estimation of Crop Biophysical Characteristics: Problems and Solutions
AU: * Gitelson, A A
EM: gitelson@calmit.unl.edu
AF: University of Nebraska, 303 Hardin Hall, Lincoln, NE 68583-0973, United States
AU: Rundquist, D C
EM: drundquist@calmit.unl.edu
AF: University of Nebraska, 303 Hardin Hall, Lincoln, NE 68583-0973, United States
AU: Keydan, G P
EM: keydan@calmit.unl.edu
AF: University of Nebraska, 303 Hardin Hall, Lincoln, NE 68583-0973, United States
AB:
Characterization of crop physiological and phenological status, or crop condition, requires robust retrievals of
important crop biophysical properties, preferably using non-destructive methods. The sensitivity of the widely
used Normalized Difference Vegetation Index (NDVI) saturates at moderate levels of aboveground biomass; i.e.,
when leaf area index (LAI) increases above about 2. We report the results of our investigation of the performance
of an advanced suite of four vegetation indices that expand the dynamic ranges of canopy biophysical properties
over high biomass surfaces. The indices are: 1) the Visible Atmospherically Resistant Vegetation Index (VARI), for
retrieving the fractional cover of green vegetation; 2) the Wide Dynamic Range Vegetation Index (WDRVI), which
allows retrieval of LAI: 3) the Green NDVI and Red Edge NDVI, designed to yield the photosynthetically active
component of total absorbed photosynthetically active radiation (fAPAR); and 4) Green and Red Edge Chlorophyll
Indices for measuring the total chlorophyll content in a vegetation canopy. We discuss the results of estimating
the biophysical characteristics noted above using close range sensing (reflectance taken 6 meters above the
canopy), an airborne imaging spectrometer and satellite observations. The techniques were tested for maize and
soybean in agricultural fields under irrigated and rainfed conditions. It is possible to accurately estimate the
fractional cover of green vegetation, the photosynthetically active component of absorbed PAR, green LAI and
chlorophyll content in crops with different canopy architectures and leaf structures with green leaf area indices
ranging from 0 to more than 6.
DE: 0402 Agricultural systems
DE: 0428 Carbon cycling (4806)
DE: 0480 Remote sensing
SC: Biogeosciences [B]
MN: 2007 Fall Meeting