CYCLOPES products. The resulting daily LAI and FPAR estimates were gap
filled and smoothed with the time series-processing algorithm developed previously for GEOV1/AVHRR. The use of the background climatology information on
LAI and FPAR values, as well as the smoothing algorithm allowed for short-term
projections required for deriving real time estimates of the products. The resulting
GEOV2/VGT products were demonstrated to be highly consistent with GEOV1/
VGT values with a large improvement in the continuity of the data (Baret et al.
2013). GEOV2/VGT is also fairly consistent with GEOV1/AVHRR and provides
thus a time series of more than 32 years of LAI and FPAR products. The GEOV
series of products are shown below in Table 2.1.
2.5 Availability of Data Products
The LAI/FPAR products as described above are available to use by the scientific
research community. The standard MODIS Collection 5 LAI/FPAR products are
available via the Reverb/ECHO web service at http://reverb.echo.nasa.gov/reverb/.
The standard MODIS products from 2000 till present are available at a spatial
resolution of 1 km and at 8 day temporal frequency. The long-term multi-year
(1981 till present) monthly AVHRR LAI/FPAR dataset based on a scaled version
of the MODIS algorithm is available upon request at the Climate and Vegetation
Research Group at http://cliveg.bu.edu/modismisr/index.html. The GEOV2 LAI/
FPAR products can be downloaded freely from the GEOLAND2 web portal
located at http://www.geoland2.eu/portal/. They are available at the dekadal time
step with 0.05° and 0.0089° spatial sampling interval in lat-lon geographic projection system. The MODIS LAI products at a spatial resolution of 250 m is also
available upon request via the NASA Earth Exchange (NEX) web portal located at
https://c3.nasa.gov/nex/. NEX in collaboration with USGS EROS is also currently
making Landsat derived LAI available to research community on demand basis.
2.6 Validation Efforts
There has been an extensive effort since the inception of the NASA EOS era to
validate biophysical products. Validation campaigns from existing network of sites
like the BigFoot, AERONET, FLUXNET, EOS Land Validation Core Sites, and
Valeri with sustained efforts from several research teams across the globe have
provided the necessary platform to validate these biophysical products (Garrigues
et al. 2008; Morisette et al. 2006; Pisek and Chen 2007). Both the MODIS and
SPOT derived LAI/FPAR products have been extensively validated over a suite of
vegetation types and climatic regimes. It is to be noted that ‘‘validation’’ refers to
both (a) direct and (b) indirect validation, where the former refers to comparing
satellite derived measures with ground truth while the later refers to an exercise
2 Green Leaf Area and Fraction of Photosynthetically
53
filled and smoothed with the time series-processing algorithm developed previously for GEOV1/AVHRR. The use of the background climatology information on
LAI and FPAR values, as well as the smoothing algorithm allowed for short-term
projections required for deriving real time estimates of the products. The resulting
GEOV2/VGT products were demonstrated to be highly consistent with GEOV1/
VGT values with a large improvement in the continuity of the data (Baret et al.
2013). GEOV2/VGT is also fairly consistent with GEOV1/AVHRR and provides
thus a time series of more than 32 years of LAI and FPAR products. The GEOV
series of products are shown below in Table 2.1.
2.5 Availability of Data Products
The LAI/FPAR products as described above are available to use by the scientific
research community. The standard MODIS Collection 5 LAI/FPAR products are
available via the Reverb/ECHO web service at http://reverb.echo.nasa.gov/reverb/.
The standard MODIS products from 2000 till present are available at a spatial
resolution of 1 km and at 8 day temporal frequency. The long-term multi-year
(1981 till present) monthly AVHRR LAI/FPAR dataset based on a scaled version
of the MODIS algorithm is available upon request at the Climate and Vegetation
Research Group at http://cliveg.bu.edu/modismisr/index.html. The GEOV2 LAI/
FPAR products can be downloaded freely from the GEOLAND2 web portal
located at http://www.geoland2.eu/portal/. They are available at the dekadal time
step with 0.05° and 0.0089° spatial sampling interval in lat-lon geographic projection system. The MODIS LAI products at a spatial resolution of 250 m is also
available upon request via the NASA Earth Exchange (NEX) web portal located at
https://c3.nasa.gov/nex/. NEX in collaboration with USGS EROS is also currently
making Landsat derived LAI available to research community on demand basis.
2.6 Validation Efforts
There has been an extensive effort since the inception of the NASA EOS era to
validate biophysical products. Validation campaigns from existing network of sites
like the BigFoot, AERONET, FLUXNET, EOS Land Validation Core Sites, and
Valeri with sustained efforts from several research teams across the globe have
provided the necessary platform to validate these biophysical products (Garrigues
et al. 2008; Morisette et al. 2006; Pisek and Chen 2007). Both the MODIS and
SPOT derived LAI/FPAR products have been extensively validated over a suite of
vegetation types and climatic regimes. It is to be noted that ‘‘validation’’ refers to
both (a) direct and (b) indirect validation, where the former refers to comparing
satellite derived measures with ground truth while the later refers to an exercise
2 Green Leaf Area and Fraction of Photosynthetically
53