Validation is the process of assessing, by independent means, the quality of the data products derived from the system outputs
Background
The subgroup on Land Product Validation (LPV) is one of six subgroups of the Working Group on Calibration and Validation (WGCV), which itself is one of two standing working groups within the Committee on Earth Observation Satellites (CEOS, see also CEOS structure (
).
The Land Product Validation subgroup arose out of the recognition in the late nineties that standardized approaches to global product validation were essential for wide acceptance and use of proposed global land products. Several programs at the time were aimed at global monitoring of Earth processes, many with plans to distribute higher level data products. A common approach to validation would encourage widespread use of validation data, and thus help us to more toward standardized approaches to global product validation. With the high cost of in-situ data collection, the potential benefits from international cooperation are considerable and obvious.
Previous requests for assistance from the original International Global Observing Strategy (IGOS) pilot projects and two subsequent ad hoc meetings of the WGCV identified a clear need for improved international collaboration concerning the validation of land products derived from Earth observing satellites. A new subgroup within the WGCV was proposed to the CEOS Plenary in Stockholm at the end of 1999, receiving full support. The LPV was officially adopted as a subgroup at the WGCV-17 meeting in October of 2000.
The guidelines for the CEOS Hierarchy of Validation (updated Oct 2009) are:
| Stage 1 Validation |
Product accuracy is assessed from a small (typically < 30) set of locations and time periods by comparison with in-situ or other suitable reference data. |
| 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 consistency 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 consistency 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. |
The LPV subgroup activities are divided up into 6 focus areas, namely biophysical products, surface radiation/albedo, fire/burn scar detection, land cover mapping, land surface temperature/emissivity, and soil moisture. Working with GOFC/GOLD, who seek the common goal of coordinated validation of land cover and fire products by standardized protocols, LPV aims for similar coordination for all land products.
A list of international cooperating agencies and groups related to CEOS and Earth observation is provided here.
More on LPV: background, previous reports, and it relationship with WGCV
and CEOS...….
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