Publication Date:
2019-05-28
Description:
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 di�erent 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 e�ective. Distinct radiometers from di�erent manufacturers operated
by di�erent 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. Uncertaint 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.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
Format:
application/pdf