The Advanced Very High Resolution Radiometer
(AVHRR) data from NOAA’s series of polar-orbiting
meteorological satellites have been used extensively to
study regional, continental, and global phenomena. The
most popular application of these data has been to monitor
and evaluate vegetation over land surfaces. Among the
available types of satellite data, AVHRR data is outstanding
for its temporal resolution (the satellites pass twice daily
above each location). This repetitive temporal monitoring
reveals patterns in the data that can be transformed into
quantitative determinations of the rates of development of
resources, and into qualitative judgments of external effects
on these resources. AVHRR NDVI has been employed in
various studies, e.g., land cover classification (DeFries &
Townshend, 1994) and biophysical parameter derivation
(Sellers et al., 1994). The two bands used to estimate NDVI
have the wavelength ranges 570–710 (Band 1) and 720–
1010 nm (Band 2), respectively (NOAA-14).
Four years of weekly composite data from 1996 to 2000
except 1999 were downloaded from the German Remote
Sensing Data Center (DFD). This weekly product is based
on NOAA-14 AVHRR data and maximum value composites
over 21 AVHRR passes during the period. Before compositing,
special emphasis is given to a precise image georegistration
and a reasonable cloud screening procedure to
ensure that only cloud free pixels are taken for the later
processing of compositing.