Uncertainty budget for Sea-Bird Scientific radiometers following
cross-site calibration
Abstract
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.