On-orbit Calibration of Staring Imaging Sensors Using Innovative Techniques and Field-deployable Instrumentation with High Radiometric and Temporal Sensitivity

The objective of this work is to expand short wave infrared (SWIR) measurement capabilities to ground-viewing radiometers (GVRs) designed, developed, tested, and deployed by the University of Arizona Remote Sensing Group (RSG) to validate the radiometric calibration of sensors onboard Earth-observing satellites. The current version GVR operates at the Radiometric Calibration Test Site (RadCaTS), a well-understood vicarious calibration facility in use by the RSG for over 10 years. RadCaTS instrumentation includes four multispectral ground-viewing radiometers, a meteorological station, and an AERONET Cimel sun photometer. A satellite uplink allows for near real-time processing. Surface reflectance and atmospheric characterization determined by RadCaTS instruments are used as inputs in MODTRAN radiative transfer code to predict top-of-atmosphere spectral radiance (or reflectance) for the time of overpass. Results validate the radiometric calibration of the sensors under test. RadCaTS currently provides NIST-traceable radiometric calibration data, without the requirement for on-site personnel, to government and commercial satellite organizations such as NASA, the European Space Agency (ESA), RapidEye, and DigitalGlobe. The purpose of this work is to validate the lifetime radiometric calibration of geostationary satellite sensors that operate in the 4002500-nm spectral range. This approach is independent of any onboard calibration systems.