Validation

The Suomi-NPP VIIRS land team adopts the Committee on Earth Observation Satellites (CEOS) validation stage heirarchy for their products. The validation stages and definitions are in the table below.

Definition of CEOS-LPV Validation Stages
0	No validation. Product accuracy has not been assessed. Product considered beta.
1	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.
2	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.
3	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 rigorous 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.
4	Validation results for stage 3 are systematically updated when new product versions are released and as the time-series expands. When appropriate for the product, uncertainties in the product are quantified using fiducial reference measurements over a global network of sites and time periods (if available).

 

For the Suomi-NPP mission, there are two major entities that support sensor calibration and EDR algorithm development and validation activities: (1) NASA's Land Science Investigator-led Processing System (SIPS); and (2) product teams within the JPSS Algorithm Development, Calibration and Validation program.

For the NASA Suomi-NPP Land Science Team, the Land SIPS also supports the processing of global land climate data records (CDRs) from the VIIRS instrument on Suomi NPP to meet the needs of NASA Earth System Science and Applied Sciences. The products produced by the SIPS include both standard and experimental products developed by the VIIRS Science Team and near real-time data products to meet the needs of NASA’s near real-time community.

The JPSS Land Product Algorithm Development and Cal/Val team utilizes key JPSS program resources. The Algorithm Development Library is a Linux-compatible environment that emulates the programming interfaces of the IDPS (an IBM AIX system), and thus facilitates algorithm changes to be integrated into the complex operational environment. The Government Resource for Algorithm Verification, Independent Testing, and Evaluation (GRAVITE), in addition to being a repository for Suomi-NPP data products for the algorithm and cal/val teams, also includes the NPOESS SIPS, a subsystem for systematically comparing Suomi-NPP products with independent data; and the Algorithm Development Area, a full-scale IDPS test system.

The NASA Land SIPS and NOAA JPSS teams engage in joint validation exercises, including in-situ and airborne measurement campaigns to maximize the performance of all Suomi-NPP Land algorithms and products.