Bridging Data Gaps in Climate Change Monitoring

NIST has published a report based on discussions at a one-day workshop entitled “Bridging Satellite Climate Data Gaps,” in the current issue of the NIST Journal of Research. The report addresses the issue of data gaps in time series of satellite measurements, which can be either intentional or unplanned. Such gaps can occur due to launch delay, launch failure, measurement inconsistencies, or data jumps in radiometric scales between satellites. Data records of interest include sea-surface temperature, ocean color, vegetation level, soil moisture, and atmospheric temperature. These gaps create added uncertainties in the small signatures of climate change.

The overarching recommendation, voiced by leading experts in the Earth Observation community, is that all calibrations and measurement procedures for space borne and aircraft sensors should be rigorously traceable to the SI. Long-term monitoring of climate change will inevitably involve piecing together data from multiple sources. This process is made particularly robust when all measurements relevant to climate change are SI traceable to accepted absolute scales.

The report summarizes the strategies required to attain SI traceability. They include continuing improvements in prelaunch, onboard, and vicarious calibrations and transfer standards; establishing celestial standards and procedures for intercomparisons; establishing SI traceability for alternative measurement strategies, such as in situ networks and airborne sensor campaigns; and leveraging international satellite assets.

Physics Laboratory sponsored the workshop on December 10, 2009 at NIST. Approximately 50 people attended, including experts from NASA, NOAA, the U.S. Geological Survey, the University of Wisconsin, Harvard University, and Utah State University. NIST also presented the results from the workshop at the SPIE Optics and Photonics Conference in San Diego in August 2010.

For further information, see Workshop on bridging satellite climate data gaps.