Salar de Uyuni Field Campaign for Independent GOES-16 ABI Solar Reflective Channel Radiance/Reflectance Validation

A field campaign was held at Salar de Uyuni, Bolivia in June 2017 to take measurements for an independent validation of the GOES-16 Advanced Baseline Imager (ABI) solar reflective channel radiometric and reflectance scale. The reflectance-based approach of vicarious calibration is used in this work: In situ measurements are taken to characterize surface reflectance and the atmosphere to constrain radiative transfer code to predict at-sensor radiance and reflectance. A 1-km square test site was identified in the north-central portion of the salt flat based on historic uniformity analysis. The geometry of the ground-based reflectance measurements was designed to match the ABI view geometry and be coincident with several image acquisitions over the 90-minute period of reflectance measurements. Six sun photometers from the Aerosol Robotic Network (AERONET) were used to take measurements at the reflectance site, around a ~15-km perimeter of the reflectance site, and at the perimeter of the large salt flat. Atmospheric properties such as aerosol optical depth, angstrom parameter, and columnar water vapor will be derived using these measurements. The campaign included six days of measurements during which the reflectance test site was measured ten times. Some of these ground measurement sets coincided with overpasses from other sensors such as Landsat 7 ETM+, Terra MODIS, Suomi NPP VIIRS, Worldview-3, and GeoEye-1. This work will 1) compare at-sensor reflectance and radiance of the test site reported by ABI and the predicted values based on the field measurements described above; 2) provide characterization of the Salar de Uyuni site to assist future sensor intercomparisons; and 3) provide a transfer among several of the sensors that imaged the test site through this campaign.