The Copernicus Program has been established through the Regulation EU No377/2014 with the objective to ensure long-term and sustained provision of accurate and reliable data on environment and security through dedicated services. Among these, the Copernicus Marine Environment Monitoring Service and the marine component of the Climate Change Service, both rely on satellite ocean colour observations to deliver data on water quality and climate relevant quantities such as chlorophyll-a concentration used as a proxy for phytoplankton biomass.
Satellite ocean colour missions require in situ highly accurate radiometric measurements for the indirect calibration (so called System Vicarious Calibration (SVC)) of the space sensor. This process is essential to minimize the combined effects of uncertainties affecting the space sensor calibration and those resulting from the inaccuracy of processing algorithms and models applied for the generation of data products.
SVC is thus a fundamental element to maximize the return on investments for the Copernicus Program by delivering to the user science community satellite ocean colour data with accuracy granting achievement of target objectives from applications addressing environmental and climate change issues.
The long-term Copernicus Program foresees multiple ocean colour missions (i.e., the Sentinel-3 satellites carrying the Ocean and Land Colour Instrument (OLCI)). The need to ensure the highest accuracy to satellite derived data products contributing to the construction of Climate Data Records (CDRs), suggests the realization, deployment and sustain of a European in situ infrastructure supporting SVC for Sentinel-3 missions, fully independent from similar facilities established and maintained by other space agencies (e.g., that operated in the Pacific Ocean by US agencies). It is emphasized that the need to cope with long-term Copernicus objectives on data accuracy, implies very stringent requirements for the in situ infrastructure and location providing reference measurements for SVC. These requirements, in fact, are much higher than those imposed by SVC for a single mission.
The content of this Report builds on the long-standing experience of the JRC on ocean colour radiometry. This experience counts on decadal field and laboratory measurements performed in support of validation and SVC applications, and additionally on activities comprehensively embracing measurement protocols, instruments characterization and the initiation of autonomous measurement infrastructures. Overall, this Report summarizes a number of recent investigations led by the JRC on SVC requirements for the creation of CDRs. The final objective is to consolidate in a single document the elements essential for the realization of a European SVC infrastructure in support of the Copernicus Program.
Briefly, the various Chapters summarize:
• General requirements for a long-term SVC infrastructure, which indicate the need for spatially homogenous oceanic optical properties, seasonal stability of marine and atmospheric geophysical quantities, negligible land perturbations, hyperspectral radiometry, and low measurement uncertainties;
• Spectral resolution requirements for in situ SVC hyperspectral measurements as a function of bandwidths and center-wavelengths of most advanced satellite sensors, which specify the need for sub-nanometre resolutions to allow for supporting any scheduled satellite ocean color sensor;
• Suitable SVC locations in European Seas showing the fitness of regions in the Eastern Mediterranean Sea to satisfy fundamental requirements.
ZIBORDI Giuseppe;
MELIN Frederic;
TALONE Marco;
Zibordi, G., Melin, F. and Talone, M., System Vicarious Calibration for Copernicus Ocean Colour Missions: Requirements and Recommendations for a European Site, EUR 28433 EN, Publications Office of the European Union, Luxembourg, 2017, ISBN 978-92-79-65329-2 (pdf),978-92-79-65330-8 (print), doi:10.2760/155759 (online),10.2760/1095 (print), JRC105497.
2017-01-24
Publications Office of the European Union
JRC105497
978-92-79-65329-2,
978-92-79-65330-8 (print),
1831-9424 (online),
1018-5593 (print),
EUR 28433 EN,
OP KJ-NA-28433-EN-N (online),
OP KJ-NA-28433-EN-C (print),
https://publications.jrc.ec.europa.eu/repository/handle/JRC105497,
10.2760/155759 (online),
10.2760/1095 (print),
