demonstrated the use of digital webcam, RGB imagery and ratios of green and red
components for detection of forest phenology. An automated tower-based, multiangular spectroradiometer platform (AMSPEC) provides continuous spectral
measures of a canopy through a range of viewing angles over all azimuthal
directions (Hilker et al. 2011).
The global network known as FLUXNET coordinates observations from a
multitude of micrometeorological tower sites (Running et al. 1999). The tower
sites use eddy covariance methods for continuous measurements of carbon, water,
Fig. 1.9 In-situ automated sensors provide continuous spectral measures of vegetation indices
for diurnal, seasonal, and interannual comparisons with satellite data. a Example of in situ NDVI
time series over varying crops (wheat, sugar beet, and mustard) in Belgium (adapted from
Soudani et al. 2012) and b comparisons of daily canopy photosynthesis from eddy flux tower and
midday LEDs derived NDVI over a California annual grassland site (Adapted from Ryu et al.
2010. Copyright (2010) Reprinted with permission from Elsevier)
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A. Huete et al.