In 2011, three improved ground-viewing radiometers (GVRs) were built and deployed to support the Radiometric Calibration Test Site (RadCaTS) developed by the Remote Sensing Group (RSG) at the University of Arizona. The GVRs are filter-based radiometers with eight spectral channels covering a wavelength range of 400-1550 nm. They are automated, field-deployable instruments capable of long-term, standalone operation. The radiometers are temperature controlled and designed for greater stability and lower noise than their light emitting diode (LED) based predecessors.

This work describes the deployment period of these radiometers with particular attention paid to the in-field performance, reliability, and results from these instruments. Using other RadCaTS inputs including meteorological station data and Aerosol Robotic Network (AERONET) Cimel sun photometer data, select vicarious calibration results are presented. With these results, an assessment of the calibration applications of the RadCaTS during new GVR deployment is discussed. In addition, GVR calibration and characterization results, including solar radiation based calibration (SRBC), are presented as another means of assessing the performance of the radiometers over deployment periods.

The Operational Land Imager (OLI) is one of two instruments onboard the Landsat 8 platform, which was launched on 11 February 2013 from Vandenberg Air Force Base in California. The multispectral bands of OLI retain the 30-m spatial resolution of Landsat 5 TM and Landsat 7 ETM+, but improvements to the system include 12-bit radiometric resolution, eight multispectral bands in the VNIR and SWIR spectral regions, and one panchromatic band. The earlier TM and ETM+ sensors use a whiskbroom configuration, while OLI uses a pushbroom configuration, which allows it to have a higher signal-to-noise ratio than previous Landsat instruments. This also creates challenges in radiometric calibration due to the large number of detectors on the 14 focal plane modules.

Long-term data continuity is a crucial component of the 40-year Landsat series of satellites, and ground-based vicarious calibration has played an important role in ensuring that these sensors remain on the same radiometric scale. This work presents the early ground-based in-flight radiometric calibration of OLI, which was determined using the traditional and well-understood reflectance-based approach, as well as the Radiometric Calibration Test Site (RadCaTS), which is an automated suite of instruments located at Railroad Valley, Nevada.