Liu, Y.Y., R.A.M. De Jeu, M.F. McCabe, J.P. Evans, A.I.J.J.M. Van Dijk
3rd International Symposium on Remote Sensing of Environment, Sydney, Australia, 10-15 April 2011.
Vegetation density plays an important role in
water and energy balance. Satellite-based optical and
microwave sensors are expected to provide complementary
vegetation information. Here we compared NDVI from
AVHRR and vegetation optical depth (VOD) from SSM/I
over Mongolia from 1988 through 2006. Both products show
similar spatial distribution in annual average and are able
to capture similar inter-annual variations. However, the
long term changes reflected by them are divergent.
Microwave based VOD shows considerable decreasing
trends over grassland, whereas NDVI shows slight declines
and even increasing trends. Further investigations are
required to identify the causes for their divergence.
Figure 4: Trend in peak monthly NDVI and VOD of each year
during 1988 – 2006 using Mann-Kendall analysis.
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Last updated 31st January 2013