Ground viewing radiometer characterization, implementation and calibration applications - A summary after two years of field deployment

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 temperaturecontrolled 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.