Advancements in the calibration and validation of Earth-observation satellite sensors using automated ground-based measurements

Abstract:

Vicarious radiometric calibration is an independent process that is used to monitor the health of Earth-observing systems. This includes both the sensor itself, as well as any onboard radiometric calibration systems. Typical methods include ground-based in situ measurements, cross calibration, lunar observations, and pseudo-invariant sites. The Remote Sensing Group at the University of Arizona has traditionally used the reflectance-based approach for the in-flight calibration of Earth-observing sensors. This requires personnel to be at a test site for a given overpass, and the increasing number of satellites on orbit make it difficult and expensive to deploy teams to collect field data. In response to this, an automated site has been developed to collect data during all clear-sky conditions. The Radiometric Calibration Test Site (RadCaTS) is located at Railroad Valley, Nevada, and it is currently being used to calibrate and validate the surface reflectance products of such sensors as Landsat 7 ETM+, Landsat 8 OLI, Terra and Aqua MODIS, Suomi NPP VIIRS, the RapidEye constellation of satellites, and more recently, Sentinel-2A MSI. An effort is also underway to create a network of instrumented test sites, and RadCaTS is currently one of four sites used in the Radiometric Calibration Network (RadCalNet) working group. This work presents the evolution of RadCaTS, current vicarious calibration results, and insight into the efforts to create a global network of instrumented sites.