POSTER SESSION 4

10:30–12:30, Thursday, September 17

Poster Session | 1 | 2 | 3 | 4 | Schedule at a Glance

ABSTRACT 1309 | POSTER 24

HOW DO WE VALIDATE VALIDATION MEASUREMENTS? INSIGHTS FROM THE 2025 FIELD INTER-COMPARISON EXERCISE (FICE)

In recent years, intercomparisons of field radiometric measurements have been conducted regularly within the framework of the Copernicus Fiducial Reference Measurements for Satellite Ocean Colour (FRM4SOC) initiative. These exercises provide an important verification step for assessing the equivalence of radiometric products derived from different instrument systems.

In 2025, the Field Inter-Comparison Exercise (FICE 2025) was conducted at the Acqua Alta Oceanographic Tower (AAOT) in the northern Adriatic Sea from 9 to 14 July. The exercise built on the findings and lessons learned from FICE 2018 (Tilstone et al., 2020) and FICE 2022 (Tilstone et al., 2025), while focusing on novel aspects centred on measurement uncertainties.

FICE-2025 relied on four TriOS RAMSES above-water systems and one Sea-Bird HyperSAS system. In contrast to earlier exercises, all instruments were manually operated, mounted on a purpose-built frame, and deployed from the same location on the platform. This protocol minimised differences arising from platform perturbations and helped to ensure that all instruments sampled the same sea-surface and sky areas. The radiometers, all benefitting from absolute calibration and of characterizations for non-ideal performance, were also aligned according to previously laboratory-verified polarisation axes, meaning that any polarisation-related effects were expected to be comparable across the instruments. All datasets were processed using the HyperInSPACE Community Processor (HyperCP).

Overall, by minimising differences in calibration, deployment geometry, and processing (with all instruments calibrated in the same laboratory, deployed from the same location, and processed using HyperCP with common settings) the study allows for verifying instrument-characterisation-related corrections and their associated uncertainties.

Agnieszka Bialek, NPL, [email protected], https://orcid.org/0000-0003-4502-2687

Giuseppe Zibordi, EOScience, [email protected]

Dirk Aurin, NASA Goddard Space Flight Center, [email protected]

Juan Ignacio Gossn, EUMETSAT, [email protected]

Krista Alikas, University of Tartu, [email protected]

Vittorio Brando, CNR-ISMAR, [email protected], https://orcid.org/0000-0002-2193-5695

Jamie Pitarch, CNR-ISMAR, [email protected]

Martin Hieronimi, Helmholtz-Zentrum Hereon, [email protected]

Pietro Sciuto, European Commission, Joint Research Centre (JRC), [email protected]

Gavin Tilstone, PML, [email protected]

Riho Vendt, University of Tartu, [email protected]

Ilmar Ansko, University of Tartu, [email protected]