In-situ and above water radiometers are a critical for validating Ocean Color Satellite measurements, used to monitor in-water constituents of the global ocean. The calibration process, instrument response characterization, and environmental measurement all contribute to the overall uncertainty budget of the radiometric measurement. An integral part of this uncertainty traceability chain is accurate laboratory calibration of radiometric sensors. Over its lifetime, the Sea-Bird Scientific Halifax site (formerly Satlantic, LP) participated in inter-laboratory comparisons to ensure the quality of its calibrations. These include: NASA’s Seventh SeaWIFS Intercalibration Round-Robin Experiment (SIRREX-7, Hooker et al. 2002), conducted in 1999, compared Halifax to the Center for Hydro-Optics and Remote Sensing (CHORS, San Diego State University, California, USA) and the Joint Research Centre (JRC, Ispra, Italy). More recently, Sea-Bird Scientific participated in the European Space Agency (ESA) sponsored Fiducial Reference Measurements for Satellite Ocean Colour (FRM4SOC) program. In 2017, Sea-Bird Scientific transitioned the manufacturing and calibration of radiometric products from the facility located in Halifax (HAL), Nova Scotia CA to the facility located in Philomath (PHI), Oregon USA (formerly WET Labs, Inc.). As part of this transition, the radiometer calibration facility was reproduced at the Philomath site and Sea-Bird Scientific conducted an extensive cross facility set of experiments to: 1. Quantify relative calibration uncertainties within and between Halifax and Philomath laboratories; 2. Quantify differences in repeatability relative to Halifax (established standard); 3. Compare relative laboratory calibration uncertainties to budget of estimated uncertainty sources; 4. Verify successful transfer of build and calibration processes at Philomath site.

Ocean color satellites require routine in-orbit verification and vicarious calibration to maintain accuracy over the mission lifetime and between satellites. The majority of vicarious calibration and validation activities for ocean color satellites are carried out in areas of uniform oceanic and atmospheric optical properties using in situ radiometric data collected from fixed mooring installations or oceanographic ships. These methods have limitations in spatial coverage and in the cost of maintenance and operation. A spatially extensive network of vicarious calibration match-up data points would aid in reducing vicarious calibration uncertainty. To meet these needs, we have developed a new approach to ocean color satellite vicarious calibration and validation. Our system (HYPERNAV) combines accurate, reliable and stable hyperspectral radiometric instruments with autonomous profiling float technologies to provide a cost effective, unattended means for vicarious calibration over periods of years in the open ocean. We present data from laboratory and field experiments of the HYPERNAV system used to characterize system performance and to quantify the end-to-end radiance uncertainty budget. We present match-up comparisons of HYPERNAV field data and coincident water leaving radiance measurements from ocean color satellites, demonstrating the capabilities of the system to provide new vicarious calibration paradigm for ocean-color remote-sensing satellites.