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The more than two-decade history of field collections by RSG has led to an assemblage of a significant instrument suite spanning the three research areas of the RSG: field, laboratory, and computing. The equipment is a mixture of commercially-available systems as well as sensors designed and built at the University of Arizona. The outcome of group’s effort is a state-of-the-art radiometric facility with primary and secondary NIST traceability. The laboratory is coupled with an array of robust field instruments that result in the flexibility to measure an array of applications with high accuracy and precision.

RSG’s vicarious calibration campaigns require instrumentation to assess the atmosphere and surface properties of our test sites. The primary atmospheric instrument is the solar radiometer. The group currently has three automated solar radiometers built at the UofA and two of the Cimel sun photometers that are part of Aeronet, including one deployed at Railroad Valley. The group maintains a meteorological station at its Railroad Valley site as well as a portable system used for all of our collections. The surface characterization makes use of three ASD FieldSpec FR spectroradiometers and one FieldSpec. There are two large-sized Spectralon panels that are used as field references as well as multiple other panels that are used as secondary references. Recent advances in field equipment has led to the deployment of a set of ground-looking radiometers built by RSG that are located at Railroad Valley to monitor surface changes throughout the year.

RSG also uses a mobile laboratory to transport equipment to, and store equipment at field sites. The laboratory has two climate-controlled compartments for troubleshooting and repairing malfunctioning field equipment. This compartment also provides shelter for personnel and computers while working at the site. Recent modifications to the mobile facility allow it to be used for micro-pulse lidar data collections. The laboratory operates off of two 10-kW generators to supply electrical power. The group has deployed the trailer for periods up to five weeks at test sites.

RSG’s past work has also led to the development of a state-of-the-art radiometric facility. The facility includes a 15-cm collimator that is used for field-of-view characterization. The spectral response of the systems and transmittance of spectral filters is measured with an Optronic Laboratories model 750 double monochromator with various source and detector modules covering the range from 280 nm to about 14 000 nm. The radiometric calibration of sensors can be determined via a 1.02-m barium sulfate sphere source with 14 bulbs and a 15-cm Spectralon sphere source with two different wattage bulbs. These sources are used for noise, stability, spatial uniformity, and other measurements. They are also used for radiometric calibrations of instruments in conjunction with a set of ultrastable cross-calibration radiometers.

The heart of RSG’s radiometric facility is a gonioradiometric laboratory to enable us to accurately measure the directional reflectance of reference reflectance panels. The normal use of the goniometer is to measure the field reflectance panels used in our reflectance-based method. Several radiometers, including a set of ultrastable transfer radiometers can be used in the facility. The RSG maintains a number of calibrated standards of spectral irradiance both directly from NIST and from third party sources traceable to NIST. These standards are used directly for irradiance calibrations of instruments and with calibrated diffusers for radiance calibrations. The RSG has the capacity to use primary, secondary, and tertiary standards of spectral irradiance (standard lamps) as well as primary standards of diffuse reflectance. The traceability ensures the best accuracy of the RSG measurements, consistency of the results, and a transfer of laboratory measurements to the field.