MODLAND Validation Background
The information
below provides an overview of the validation strategy being
implemented by the MODLAND team, a description of the three
stages of a 'Validation Hierarchy', and related references.
Overall Approach
MODLAND product quality is ensured
by Calibration, Quality Assurance (QA) and Validation.
MODLAND uses several validation techniques to develop uncertainty
information on its products. These include comparisons with in
situ data collected over a distributed set of validation
test sites, comparisons with data and products from other airborne
and spaceborne sensors (e.g., SeaWiFS, AVHRR, MISR, TM/ETM+,
ASTER), inter-comparison of trends derived from independently
obtained reference data and MODLAND products, and analysis
of process model results (including EOS IDS models) which are
driven
or constrained by MODLAND products.
MODLAND's primary validation technique includes the collection
of and comparison with field and aircraft data, and comparison
with data and products from other satellites. The infrastructure
for these efforts has resulted in the establishment of
a semi-permanent set of EOS Land Validation Core Sites, most of
which include a flux tower, for extended temporal measurement
of terrestrial biophysical dynamics over a range of landcover
types. Field data are archived in cooperation with the
Oak Ridge DAAC's Mercury system.
Results of all validation activities are conveyed to the
end-user through both published literature and "Product Specific
Validation information" posted on the MODLAND validation web
page.
Validation Hierarchy
- Stage 1 Validation: Product
accuracy has been estimated using a small number of independent
measurements
obtained from selected locations and time periods and ground-truth/field
program effort.
- Stage 2 Validation: Product accuracy has
been assessed over a widely distributed set of locations
and time periods via several ground-truth and validation
efforts.
- Stage 3 Validation: Product accuracy has
been assessed and the uncertainties in the product well established
via independent measurements in a systematic and statistically
robust way representing global conditions.
Measures of Success
Successful validation is accomplished
if timely and accurate product uncertainty information becomes
routinely available
to the product users. Product-specific Validation
information is now posted
on the MODLAND validation web pages via the 
button. As
improvements and modifications to MODIS algorithms develop,
this validation information will
be updated - with
the goal of providing accuracy statements for the most current
version
of each MODLAND product.
Validation Plans
Validation Update for Terra and Aqua 
,
released December, 2000
The original MODLAND Validation Plan (September
1998) describes:
- coordination with EOS Validation Investigators
- validation sites
- pre-launch activities
- post-launch activities
- implementation of validation results
Additional
MODIS Validation References
Morisette, J. T., J.L. Privette,
and C.O. Justice, A framework for the validation of MODIS land
products, Remote
Sensing of Environment, 83(1-2),
77-96, 2002.
ORNL DAAC's "Best Practices for Preparing Ecological and Ground-Based
Data Sets to Share and Archive", published in
October, 2000.
"EOS Land Validation Coordination: An Update",
1998, by Chris Justice, Dave Starr, Diane Wickland, Jeff Privette,
and
Tim Suttles.
"EOS Global Land Validation Network" ,
Jeffrey L. Privette, Jeffrey T. Morisette, Chris Justice, and David Starr, IGARSS'99 Proceedings.
and Accessibility Certification