Laboratory Intercomparison of Radiometers Used for Satellite Validation in the 400–900 nm Range
Viktor Vabson 1,*, Joel Kuusk 1
, Ilmar Ansko 1, Riho Vendt 1, Krista Alikas 1, Kevin Ruddick 2, Ave Ansper 1, Mariano Bresciani 3, Henning Burmester 4, Maycira Costa 5, Davide D’Alimonte 6, Giorgio Dall’Olmo 7, Bahaiddin Damiri 8, Tilman Dinter 9, Claudia Giardino 3, Kersti Kangro 1, Martin Ligi 1, Birgot Paavel 10, Gavin Tilstone 7, Ronnie Van Dommelen 11, Sonja Wiegmann 9, Astrid Bracher 9, Craig Donlon 12 and Tânia Casal 12
, Ilmar Ansko 1, Riho Vendt 1, Krista Alikas 1, Kevin Ruddick 2, Ave Ansper 1, Mariano Bresciani 3, Henning Burmester 4, Maycira Costa 5, Davide D’Alimonte 6, Giorgio Dall’Olmo 7, Bahaiddin Damiri 8, Tilman Dinter 9, Claudia Giardino 3, Kersti Kangro 1, Martin Ligi 1, Birgot Paavel 10, Gavin Tilstone 7, Ronnie Van Dommelen 11, Sonja Wiegmann 9, Astrid Bracher 9, Craig Donlon 12 and Tânia Casal 12
1
Tartu Observatory, University of Tartu, 61602 Tõravere, Estonia
2
Royal Belgian Institute of Natural Sciences, 1000 Brussels, Belgium
3
National Research Council of Italy, 21020 Ispra, Italy
4
Helmholtz-Zentrum Geesthacht, Institute for Coastal Research, 21502 Geesthacht, Germany
5
University of Victoria, Victoria, BC V8P 5C2, Canada
6
Center for Marine and Environmental Research, University of Algarve, 8005-139 Faro, Portugal
7
Plymouth Marine Laboratory, Plymouth PL1 3DH, UK
8
Cimel Electronique S.A.S, 75011 Paris, France
9
Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, D-27570 Bremerhaven, Germany
10
Estonian marine institute, University of Tartu, 12618 Tallinn, Estonia
11
Satlantic; Sea Bird Scientific, Bellevue, WA 98005, USA
12
European Space Agency, 2201 AZ Noordwijk, The Netherlands
*
Author to whom correspondence should be addressed.
Remote Sens. 2019, 11(9), 1101; https://doi.org/10.3390/rs11091101
Received: 25 March 2019 / Revised: 2 May 2019 / Accepted: 5 May 2019 / Published: 8 May 2019
(This article belongs to the Special Issue Fiducial Reference Measurements for Satellite Ocean Colour)
Abstract
An intercomparison of radiance and irradiance ocean color radiometers (The Second Laboratory Comparison Exercise—LCE-2) was organized within the frame of the European Space Agency funded project Fiducial Reference Measurements for Satellite Ocean Color (FRM4SOC) May 8–13, 2017 at Tartu Observatory, Estonia. LCE-2 consisted of three sub-tasks: 1) SI-traceable radiometric calibration of all the participating radiance and irradiance radiometers at the Tartu Observatory just before the comparisons; 2) Indoor intercomparison using stable radiance and irradiance sources in controlled environment; and 3) Outdoor intercomparison of natural radiation sources over terrestrial water surface. The aim of the experiment was to provide one link in the chain of traceability from field measurements of water reflectance to the uniform SI-traceable calibration, and after calibration to verify whether different instruments measuring the same object provide results consistent within the expected uncertainty limits. This paper describes the activities and results of the first two phases of LCE-2: the SI-traceable radiometric calibration and indoor intercomparison, the results of outdoor experiment are presented in a related paper of the same journal issue. The indoor experiment of the LCE-2 has proven that uniform calibration just before the use of radiometers is highly effective. Distinct radiometers from different manufacturers operated by different scientists can yield quite close radiance and irradiance results (standard deviation s < 1%) under defined conditions. This holds when measuring stable lamp-based targets under stationary laboratory conditions with all the radiometers uniformly calibrated against the same standards just prior to the experiment. In addition, some unification of measurement and data processing must be settled. Uncertainty of radiance and irradiance measurement under these conditions largely consists of the sensor’s calibration uncertainty and of the spread of results obtained by individual sensors measuring the same object. View Full-TextKeywords:
ocean color radiometers; radiometric calibration; indoor intercomparison measurement; agreement between sensors; measurement uncertainty
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
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Vabson, V.; Kuusk, J.; Ansko, I.; Vendt, R.; Alikas, K.; Ruddick, K.; Ansper, A.; Bresciani, M.; Burmester, H.; Costa, M.; D’Alimonte, D.; Dall’Olmo, G.; Damiri, B.; Dinter, T.; Giardino, C.; Kangro, K.; Ligi, M.; Paavel, B.; Tilstone, G.; Van Dommelen, R.; Wiegmann, S.; Bracher, A.; Donlon, C.; Casal, T. Laboratory Intercomparison of Radiometers Used for Satellite Validation in the 400–900 nm Range. Remote Sens. 2019, 11, 1101.
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