Istanbul 2004 International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV. Part B4. Istanbul 2004
level of greenup. The extent and significance of the change
varies with the presence of precipitation. An examination of the
difference image comparing total precipitation to FPAR change
shows that there is a fairly constant greenup in areas having
little or no precipitation (i.e. «40 mm) and a greater difference
in those areas receiving more than 40 mm (Table 2). An
examination of the ratio images and values shows
approximately 11% change for those areas receiving less than
40 mm of rain with a dramatic change from approximately 13%
change for those areas receiving 30-40 mm to as much as 22%
change for those receiving more than 70 mm of total
precipitation over the 8-day study period (Table 3).
This study shows that the 8-day composite FPAR data can be
used to show even relatively modest changes in vegetation in
the semi-arid grasslands of Northeastern New Mexico. As such,
near real-time MODIS FPAR data can make a valuable
contribution to the integrated and active management of the
grassland environment. By providing timely information on
vegetation response to localized rainfall, decisions on irrigation
and grazing allocation can be tailored to meet grazing needs
while minimizing impacts and maximizing sustainability.
| rl Future work will focus on the lag time from precipitation events
1 | to the occurrence of the vegetative green-up. Analysis of the
— e relationship of FPAR values to grassland health will also be
Ops investigated as this is an important factor in semi-arid
environments and areas highly dependent on local precipitation
events. This and future work can provide a basis for
streamlining both FPAR and NEXRAD data for managers of
( grasslands and livestock and can provide valuable input into a
— system for real time management of the grassland resource.
4. REFERENCES
Y. Knyazikhin, J. Glassy, J. L. Privette, Y. Tian, A. Lotsch, Y.
Zhang, Y. Wang, J. T. Morisette, P. Votava, R.B. Myneni, R. R.
Nemani, S. W. Running, MODIS Leaf Area Index (LAI) and
Fraction of Photosynthetically Active Radiation Absorbed by
Vegetation (FPAR) Product (MODI5) Algorithm Theoretical
Basis Document, http://eospso.gsfc.nasa.gov/atbd/
modistables.html, 1999.
Myneni, R., Knyazikhin, Y., Glassy, J., Votava, P., Shabanov,
N., 2003, "User's Guide FPAR, LAI (ESDT: MODI15A2) 8-day
Composite NASA MODIS Land Algorithm,” Terra MODIS
Land Team, http://cybele.bu.edu/modismisr/products/modis/
userguide.pdf (accessed 2 Feb 2004).
Members of the MODIS Characterization Support Team
(MCST), 2003, “MODIS Level IB Product User's Guide",
Document #PUB-01U-0202-REV B, NASA/Goddard Space
Flight Center, Greenbelt, MD, 2003.
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