Giuseppe Zibordi

The Coastal Atmosphere & Sea Time Series (CoASTS) and the Bio-Optical mapping of Marine optical Properties (BiOMaP) programs were conceived and implemented to assist ocean color applications with field measurements of apparent and inherent optical properties, as well as concentration of optically significant water constituents. The CoASTS program led to the creation of time-series of bio-optical measurements at the “Acqua Alta” Oceanographic Tower (AAOT) site in the northern Adriatic Sea continued from 1995 up to 2016. The BiOMaP program supported the collection of equivalent bio-optical measurements across European Seas from 2000 up to 2022. This work focusses on CoASTS and BiOMaP hyperspectral absorption coefficients of optically significant constituents as determined applying standardized instruments, community measurement methods, extended quality control schemes and consolidated processing. The work, which complements a previous one by Zibordi and Berthon (2024) centred on multi-spectral data, presents the CoASTS and BiOMaP hyperspectral absorption coefficients of pigmented and non-pigmented particles in the 400–750 nm interval, and colored dissolved organic matter in the 350–680 nm one, both with a 3 nm spectral resolution at 2 nm increment. The data are available at https://doi.org/10.1594/PANGAEA.993510 (Berthon and Zibordi 2026).

A global in situ dataset for validation of satellite products from the ESA Ocean Colour Climate Change Initiative (OC-CCI) is presented. This version of the compilation, with data starting in 1996, extends to 2025, which is important for the validation of recent algorithms and satellite products. The dataset comprises in situ observations of the following variables: spectral remote-sensing reflectance (rrs), chlorophyll-a concentration ("chla"; HPLC and fluorometric), spectral inherent optical properties (IOPs: algal pigment absorption "aph", detritus plus gelbstoff absorption "adg", and particle backscattering "bbp"), spectral diffuse attenuation coefficient (kd) and total suspended matter (tsm). Data were obtained from multiple archives acquired via open internet services, or from individual projects, acquired directly from data providers. Compared to the previous version (Valente et al., 2022) this release incorporates updates from existing sources and introduces data from 13 additional sources. Notably, AERONET-OC coverage has been significantly expanded (39 sites compared to 11 in v2022) and MOBY Platinum data have been included from 2024. Methodologies were implemented for homogenisation, quality control and merging of all data. Minimal changes were made to the original data, other than conversion to a standard format, elimination of some points after quality control and averaging of observations that were close in time and space. The harmonisation procedures also include the application of a bidirectional reflectance distribution function (BRDF) correction to "rrs". The result is a merged table available in text format. Overall, the dataset increased by ~115 %, reaching 319,183 rows, with each row representing a unique station in space and time (cf 148,432 rows in Valente et al., 2022). Records of chlaovera increased by ~31 % (82,543 to 107,922); "rrs" observations nearly doubled +94 % (68,641 → 133,325); IOPs showed substantial expansion, with aph increasing by ~150 % (4,265 to 10,655) and adg by 78 % (1,654 to 2,948). The most pronounced change was for bbp, which increased by ~10,258 % (792 to 82,033), while moderate increases were observed for kd (+30 %; 2,454 to 3,197) and "tsm" (+51 %; 1,546 to 2,334). Metadata of each in situ measurement (original source, cruise or experiment, principal investigator) are included in the final table. By making the metadata available, provenance is better documented, and it is also possible to analyse each set of data separately. The compiled data are available at (Salem et al., 2026).

Spectral correction factors for the removal of glint perturbations in above-water radiometric measurements are theoretically computed for representative inland, coastal and open-ocean waters, accounting for spectral and atmospheric dependences. The simulation framework relies on the measurement protocol adopted by AERONET-OC and endorsed by the ocean color community to support the validation of satellite aquatic radiometric products. The theoretical computation of the correction factors, here termed glint correction factors or -factors, is performed in the 340–1020 nm spectral range by coupling i. a highly accurate plane-parallel scalar code to simulate the angular distribution of the spectral sky-radiance impinging at the water surface, with ii. a three-dimensional Monte Carlo code to model radiance reflections at a wind-roughened water surface. The impact of glint due to sky-radiance originating from the sun region (conventionally termed sun-glint) is separately discussed. Computed glint correction factors—for both the total sky radiance and its sole diffuse component—are available at Zenodo (https://doi.org/10.5281/zenodo.20609990).

Spectral correction factors for the removal of glint perturbations in above-water radiometric measurements are theoretically computed for representative inland, coastal and open-ocean waters, accounting for spectral and atmospheric dependences. The simulation framework relies on the measurement protocol adopted by AERONET-OC and endorsed by the ocean color community to support the validation of satellite aquatic radiometric products. The theoretical computation of the correction factors, here termed glint correction factors or -factors, is performed in the 340–1020 nm spectral range by coupling i. a highly accurate plane-parallel scalar code to simulate the angular distribution of the spectral sky-radiance impinging at the water surface, with ii. a three-dimensional Monte Carlo code to model radiance reflections at a wind-roughened water surface. The impact of glint due to sky-radiance originating from the sun region (conventionally termed sun-glint) is separately discussed. Computed glint correction factors—for both the total sky radiance and its sole diffuse component—are available at Zenodo (https://doi.org/10.5281/zenodo.20609990).

The Coastal Atmosphere & Sea Time Series (CoASTS) and the Bio-Optical mapping of Marine optical Properties (BiOMaP) programs were conceived and implemented to assist ocean color applications with field measurements of apparent and inherent optical properties, and concentration of optically significant water constituents. The CoASTS program led to the creation of time-series of bio-optical measurements at the Acqua Alta Oceanographic Tower (AAOT) site the northern Adriatic Sea continued from 1995 up to 2016. The BiOMaP program supported the collection of equivalent bio-optical measurements across European Seas from 2000 up to 2022. This work focusses on CoASTS and BiOMaP hyperspectral absorption coefficients of optically significant constituents as determined applying standardized instruments, community measurement methods, extended quality control schemes and consolidated processing codes. The work, which complements a previous one by Zibordi and Berthon (2024) centred on multi-spectral data, presents the CoASTS and BiOMaP hyperspectral absorption coefficients of pigmented and non-pigmented particles in the 400–750 nm, and of colored dissolved organic matter in the 350–680 nm interval, both with a 3 nm spectral resolution at 2 nm increment.

Unmanned aerial vehicles (UAVs), commonly referred to as drones, offer an innovative alternative to in situ measurements performed from fixed structures or ships. Within such a general framework, this work presents the “Hyperspectral Drone-based system for above-water Radiometric Acquisitions” (HYDRA), conceived for measurements specifically supporting the validation of satellite aquatic radiometric data products. By relying on consolidated measurement methods and a class of extensively characterized hyperspectral radiometers, HYDRA comprises the UAV platform allowing to quantify the radiance from the water L _T and a complementary ground-based station to measure the sky-radiance L _i and the downward irradiance E _S . Field measurements to evaluate the performance of the system were carried out in the northern Adriatic Sea in the proximity of the Acqua Alta Oceanographic Tower (AAOT) during almost ideal conditions determined by sun clear from clouds, sea state lower than 2 (WMO scale), cloud cover lower than 2 oktas, and wind speed below 3 m s ⁻¹ . During these tests, HYDRA L _T measurements were complemented by independent and concurrent L _T measurements performed at the AAOT using a hyperspectral radiometer belonging to the same class as that operated on the UAV. Matchups of HYDRA and AAOT L _T showed mean spectral differences generally ranging between 0% and +1% in the 400–580-nm interval and within ±1% in the 580–700-nm interval. The same differences characterized HYDRA and AAOT R _RS spectra as a result of the application of the same L _i and E _S values.

System vicarious calibration (SVC) enhances the accuracy of satellite ocean color radiometric data products by removing the bias due to the intrinsic inaccuracies affecting both the responsivity of the space sensor and the correction for the atmospheric and sea surface contributions to the measured signal. Various SVC procedures have been implemented and applied for regional studies, specific mission goals, and the most challenging quantification of global long-term climate-driven changes that require accurate and consistent data products across multiple missions. This paper summarizes the outcome of a workshop organized by the ocean color SVC task force of the International Ocean Color Coordinating Group (IOCCG) to review requirements for SVC supporting ocean color missions for climate and global long-term operational applications. The work emphasizes the essential need for long-term sustained SVC infrastructures and associated services, summarizes the primary requirements for establishing a comprehensive ocean color SVC framework, and provides directions for new investigations to tackle arising needs on SVC advancements and methods. Significance Statement: System vicarious calibration is the process applied to satellite ocean color missions to achieve the required accuracy over time for data products targeting climate and global long-term operational applications. This process requires access to dedicated long-term marine infrastructures and services to sustain the creation of consistent multimission time series. Aiming at unifying system vicarious calibration across missions managed by independent space agencies, this work streamlines the requirements for establishing the necessary infrastructures and services, standardizing the methods, and providing guidance to new advancements as well as maintaining current capabilities to enable steady linkage to historical satellite ocean color missions.

The Coastal Atmosphere and Sea Time Series (CoASTS) and Bio-Optical mapping of Marine Properties (BiOMaP) programs produced bio-optical data supporting satellite ocean color applications for more than 2 decades. Specifically, relying on the Acqua Alta Oceanographic Tower (AAOT) in the northern Adriatic Sea, from 1995 till 2016 CoASTS produced time series of marine water apparent and inherent optical properties, in addition to the concentration of major optically significant water constituents. Almost concurrently, from 2000 till 2022 BiOMaP produced equivalent spatially distributed measurements across major European seas. Both CoASTS and BiOMaP applied standardized instruments, measurement methods, quality control schemes and processing codes to ensure temporal and spatial consistency in data products. This work presents the CoASTS and BiOMaP near-surface data product, named CoASTS-BiOMaP, which is of relevance to ocean color bio-optical modeling and validation activities. The data are available at https://doi.org/10.1594/PANGAEA.971945 (Zibordi and Berthon, 2024).

The Coastal Atmosphere & Sea Time Series (CoASTS) and the Bio-Optical mapping of Marine optical Properties (BiOMaP) programs produced bio-optical data supporting satellite ocean color applications for almost two decades. Specifically, relying on the Acqua Alta Oceanographic Tower (AAOT) in the northern Adriatic Sea, from 1995 till 2016 CoASTS delivered time series of marine water apparent and inherent optical properties, in addition to the concentration of major optically significant water constituents. Almost concurrently, from 2000 till 2022 BiOMaP produced equivalent spatially distributed measurements across major European Seas. Both, CoASTS and BiOMaP applied equal standardized instruments, measurement methods, quality control schemes and processing codes to ensure temporal and spatial consistency to data products. This work presents the CoASTS and BiOMaP near surface data products, named CoASTS-BiOMaP, of relevance for ocean color bio-optical modelling and validation activities.