ProVal: A New Autonomous Profiling Float for High Quality Radiometric Measurements
|Author(s)||Leymarie Edouard1, Penkerc'h Christophe1, Vellucci Vincenzo1, Lerebourg Christophe2, Antoine David1, 3, Boss Emmanuel4, Lewis Marion R.5, D'Ortenzio Fabrizio1, Claustre Herve1|
|Affiliation(s)||1 : Sorbonne Univ, CNRS, LOV, F-06230 Villefranche Sur Mer, France.
2 : ACRI ST, Sophia Antipolis, France.
3 : Curtin Univ, Sch Earth & Planetary Sci, Remote Sensing & Satellite Res Grp, Perth, WA, Australia.
4 : Univ Maine, Sch Marine Sci, Orono, ME USA.
5 : Dalhousie Univ, Dept Oceanog, Halifax, NS, Canada.
|Source||Frontiers In Marine Science (2296-7745) (Frontiers Media Sa), 2018-11 , Vol. 5 , N. 437 , P. 18p.|
|WOS© Times Cited||16|
|Keyword(s)||autonomous profiling floats, remote sensing reflectance, ocean color, validation, system vicarious calibration, austral ocean, Mediterranean Sea, radiometric measurement|
An efficient system to produce in situ high quality radiometric measurements is compulsory to rigorously perform the vicarious calibration of satellite sensors dedicated to Ocean Color Radiometry (OCR) and to validate their derived products. This requirement is especially needed during the early stages of an OCR satellite activity or for remote areas poorly covered by oceanographic cruises with possible bio-optical anomalies. Taking advantage of Argo's profiling float technology, we present a new autonomous profiling float dedicated to in situ radiometric measurements. The float is based on the Provor CTS5 (manufacturer NKE) with an added novel two protruding arm design allowing for sensor redundancies, shading mitigation and near-surface data. Equipped with two identical radiometers on each arm that measure downward irradiance and upwelling radiance at seven wavelengths, the ProVal float generates both redundant radiometric profiles as well as an estimate of Remote Sensing Reflectance. Results from 449 profiles obtained in the NW Mediterranean Sea and in the Indian sector of the Southern Ocean are presented to illustrate the ProVal float technical maturity. Analysis of the behavior of the profiling float, including tilting and ascent speeds is presented. The vertical stability of the ProVal exhibits 85% of surface data of the Mediterranean Sea with a tilt smaller than 10 degrees. This percentage is 40% in the Southern Ocean due to rougher seas. Redundant sensors provide a characterization of the relative drift between sensors over the deployment which is found to be <0.15% per month over a year. Post-cruise calibration of a recovered float revealed no significant drift. As an example of the utility of ProVal floats, a match-up of Remote Sensing Reflectance measured with the European Space Agency Ocean and Land Color Imager (OLCI onboard Sentinel-3A) is shown. It follows that profiling floats, such as ProVal, could provide a significant contribution to an upcoming global System Vicarious Calibration of space-based radiometers.