International SI-traceable Laboratory inter-comparison experiment in Tartu Observatory and Kääriku

Mari Allik | 15.05.2017

Tartu Observatory organized a laboratory inter-comparison  on 8 – 13 May  2017 in the cleanroom laboratories and Lake Kääriku within the FRM4SOC project. The core action of the FRM4SOC project is to ensure that ground-based measurements of ocean colour parameters are traceable to SI standards in support of ensuring high quality and accurate Sentinel-2 MSI and Sentinel-3 OLCI products. 

FRM4SOC 2017 LCE-2

Participants from Germany (Alfred-Wegner-Institut; Helmholtz-Zentrum Geesthacht), Belgium (Royal Belgian Institute of Natural Sciences), Italy (National Research Council of Italy), Portugal (University of Algarve), Canada (University of Victoria; Satlantic), United Kingdom (Plymouth Marine Laboratory; National Physical Laboratory), France (Cimel Electronique S.A.S), European Space Agency and Estonia (Tartu Observatory; University of Tartu) took part in the inter-comparison.

The first three days were spent in Tartu Observatory’s cleanroom laboratories for optical measurements to provide SI-traceable radiometric calibration for participating radiometers and perform laboratory inter-comparison of radiometers in controlled environment. The SI-traceable calibration verifies whether different instruments measuring the same object can provide consistent results within the uncertainty limits.

The outdoor inter-comparison was carried out on the last two days on a diving platform by Lake Kääriku. The Field Ocean Color Radiometers were mounted on racks over the water surface to measure the downwelling irradiance, sky radiance and total water surface radiance.

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