Vegetation Productivity

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A FIRST LOOK AT THE MODIS 8-DAY PSN DATA FOR 2001
MODIS Science Team Mtg 19 December 2001 Steven
W. Running NTSG, Univ. of Montana
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MODIS Photosynthesis
The Monteith equation.
Absorbed Photosynthetically Active Radiation
Radiation Use Efficiency
GPP
x
APAR
(FPAR) (0.45Rnet )
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MODIS Photosynthesis
Epsilon is the slope of the line described by
GPP ? APAR
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Radiation Use Efficiency
? ?max mtmin mvpd
The coefficients are calculated from daily
minimum and maximum air temperature which are
therefore necessary inputs to the model
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VPD Tmin Coefficients
Grassland Biome
All Biomes
Tmin_max
Tmin_min
VPD
Tmin
Tmin_max Tmin_min are Tabulated by biome
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ESTIMATION OF DAILY NPP IN MOD17 ALGORITHM
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MODIS 8-day PSN Winter 2001
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MODIS 8-DAY PSN SUMMER 2001
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MODIS 8-day LAI Product
Park Falls forest site 17MAY2001 16OCT2001
The variability in LAI around the flux tower is
shown by the scatter of blue (3x3 km) and green
(5x5 km) dots.
LAI of center pixel
LAI field data Co-Kriged Aug 2000 Gower et al.
Land Cover around tower Davis et al.
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MODIS Cutouts fPAR for Park Falls
All pixels in 5x5 cutout Greenrejected Blueaccep
ted
Accepted pixels
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FLUXNET GRASSLAND SITES
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FLUXNET FOREST SITES
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SUMMARY3 Sources of
variability of MODIS PSN1. Radiometric MODIS
FPAR and LAI2. Meteorological DAO IPAR and
Temps3. Ecological MOD 17 representation of
plant physiologyEach require a different mode
of validation