Methods, Traceability and Validation of the In-Water Ocean Color Measurements

Water leaving radiance is a key parameter for ocean colour (OC) satellite radiometry. It is the basis for higher order products (e.g. chlorophyll a) and subsequent spatiotemporal analyses. Measurement schemes for in situ above-water radiometry are already well addressed, but in-water measurements, despite considered more accurate, still need attention. Optical laboratory facilities at Tartu observatory will be advanced to allow the characterization and calibration of in-water radiometers, assuring the traceability of a measurement and uncertainty budget derivation when moving from controlled laboratory to variable outdoor conditions. Outdoor comparisons of common radiometers in various deployment strategies, together with the development of new sensor prototype will help the community to optimize the in-water measurements. This allows producing traceable in situ measurements required for every OC satellite mission for validation, vicarious calibration and algorithm development.