NASA collects vast volumes of Earth observation data, but these raw data almost always require validation before they are useful in scientific studies. In general, NASA data products start at a beta or provisional level, for which little is known of the data quality. With time—through validation, algorithm improvement, and independent scientific use—much is learned about the data product and its quality. These activities increase the maturity level of the data product.
Validated data products have 4 levels with the highest level, Level 4 or L4, representing high-quality, well-validated data suitable for use in climate study. Because both data products and data validation change over time, product maturity assessments are often re-determined annually by NASA data centers.
Beta
Products intended to enable users to gain familiarity with the parameters and the data formats. Beta products are not intended for use in scientific research.
Provisional
Product was defined to facilitate data exploration and process studies that do not require rigorous validation. These data are partially validated and improvements are continuing; quality may not be optimal since validation and quality assurance are ongoing. Provisional products are not intended for use in scientific research.
Validated
Products are high quality data that have been fully validated and quality checked. Validated data are deemed suitable for systematic research into long-term studies such as climate change as well as for shorter term process studies. These are publication quality data with well-defined uncertainties, but they are also subject to continuing validation, quality assurance, and further improvements in subsequent versions. Users are expected to be familiar with quality summaries of all data before publishing results based on the data; when in doubt, contact the appropriate instrument team.
Stage 1 Validation
Product accuracy is 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 peer-reviewed literature.
Stage 3 Validation
Product accuracy has been assessed. 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 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.