MODLAND Validation Background
below provides an overview of the validation strategy being
implemented by the MODLAND team.
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 which are driven or constrained by MODLAND products. Additional land validation activities can be found on
the CEOS WGCV Land Product Validation web site (lpvs.gsfc.nasa.gov).
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 MODIS LAND (MODLAND) validation web page under the Val Status button.
- 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 efforts.
- Stage 2 Validation: Product accuracy is estimated over a significant set of locations and time periods by comparison with reference in situ or other suitable reference data. Spatial and temporal consistency of the product and with similar products has been evaluated over globally representative locations and time periods. Results are published in the peer-reviewed literature.
- Stage 3 Validation: Uncertainties in the product and its associated structure are well quantified from comparison with reference in situ or other suitable reference data. Uncertainties are characterized in a statistically robust way over multiple locations and time periods representing global conditions.
Spatial and temporal consistency of the product and with similar products has been evaluated over globally representative locations and periods.
Results are published in the peer-reviewed literature.
- Stage 4 Validation: Validation results for stage 3 are systematically updated when new product versions are released and as the time-series expands
Measures of Success
Successful validation is accomplished
if timely and accurate product uncertainty information becomes
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
of each MODLAND product.
Terra and Aqua Validation Plans
The original MODLAND Validation Plan (September
- coordination with EOS Validation Investigators
- validation sites
- pre-launch activities
- post-launch activities
- implementation of validation results
Additional MODIS Validation References
Global validation of EOS land products, lessons learned and future challenges: A MODIS case study, J. Nightingale, Nickeson, J.E., Justice, C.O., Baret, F., Garrigues, S., Wolfe, R., Masuoka, E., 2008, 33rd Proc. of the International Symposium on Remote Sensing of Environment, Stresa, Italy.
Coordinating Earth Observing System Validation, J.E. Nickeson, Morisette, J.T., Privette, J.L., Justice, C.O., Wickland, D.E., 2007, Eos Trans. AGU, 88(7).
A framework for the validation of MODIS land
products, Morisette, J.T., J.L. Privette, and C.O. Justice, , Remote Sensing of Environment, 83(1-2), 77-96, 2002.
Best Practices for Preparing Ecological and Ground-Based
Data Sets to Share and Archive, ORNL DAAC, published in October, 2000.
"EOS Global Land Validation Network" ,
Jeffrey L. Privette, Jeffrey T. Morisette, Chris Justice, and David Starr, IGARSS'99 Proceedings.