Action #4: Biogeochemical data and ocean colour products

Objectives: Harmonise and implement joint QC for regional data (biogeochemical and optical) to improve regional ocean colour (OC) and BGC regional models products. This action will consist in the elaboration of matchups between OC derived products and in situ measurements (Chla, SPM, turbidity, IOP) for the whole PSS. For regional models, there is still a need of in-situ data to evaluate the performance of BGC models, including nutrients (nitrate, phosphate, silicate), oxygen, chlorophyll-a, and carbon-related variables (pH, pCO2, DIC, ALK, DOC, POC).

At the end, this action will establish the needs in terms of BGC/optical variables for in situ coastal observations to improve models and quality of ocean color products for coastal waters. It will help to elaborate new BGC indicators for the NW-MED, indicators useful for end-users and stakeholders: acidification (pH indicator), eutrophication/hypoxia (nutrient and oxygen indicators), HABs (chlorophyll-based indicator), and water quality (chlorophyll-based indicator or SST) with applications for future CMEMS services. [Action is a combination of original topics v and vi]

Action Lead and other Partners (with contact persons): CNRS (Coppola, Doxaran, Ulses), SOCIB (Allen)

JS3 Platforms included: Several JERICO platforms: gliders, coastal moorings, buoys, repeated R/V cruises. Other platforms: ocean colour satellite products, Argo floats

Other data sources and external partners for implementation: Other data sources include CMEMS, in situ data for cal/val (BOUSSOLE), coastal gliders from CNRS, model SIROCCO SYMPHONIE-Eco3MS from CNRS and Mercator BGC forecasting models. The Action connects to external partners ACRI, MERCATOR and LEGOS.

Overall timetable of action: Spring 2021 – summer 2022

Description of action: For BGC regional models, a focus of CO2 variables and O2 between the water column and the atmosphere in the shelf area is planned in the Gulf of Lion (SIROCCO SYMPHONIE-Eco3MS). The BGC in situ data will also be used in assimilation, a field under development at Mercator as well as at our European partners within the framework of CMEMS. For the coastal environment, the aim is to improve river inputs (nutrients, carbon, and suspended solids) as well as exchanges with the sediment. For OC products, cal/val method will be applied for coastal waters using existing in situ data and algorithms.

The Action aims to avoid duplication of efforts by coordination of existing and new infrastructures across the PSS observing and forecasting platforms and networks. It will adopt common strategies, standards, and dissemination routes with a focus on common EOVs.  

The Action will use the regional knowledge of marine BGC to support the QC procedures and the validation of OC derived products compared to in situ data. The spatial representation of OC products will complete the punctual sampling of in situ sensors (gliders, buoys) and could provide a consistent and comprehensive picture of the daily situation.

Having identified societal and scientific requirements for biogeochemical observations, monitoring, and forecasting, we will coordinate existing infrastructures to leverage the individual elements for connective multi-parameter analyses across the NW-MED region.

The BGC platforms are already active in the PSS area. For satellite QC products, the in situ sampling points will be listed and will be used for the automatic matchup tool. For moving devices, a list of locations will be updated every week/month to compute and deliver the matchups.

Best practices used or developed: The Action applies best practices developed in EURO-ARGO ERIC and EMSO-ERIC

Data flows: BGC EOV observation data flows into EMODnet. Satellite products are obtained from CMEMS, EUMETSAT and HERMES data server. SYMPHONIE-ECO3M & Mercator products are available in CMEMS

Data QC routines: Automatic flags (clouds, haze, glint, hilt) are implemented in satellite data processing software (e.g., in the Sentinels Application Platform: Protocols have been defined and recently updated for ocean Color product validations in comparison with in situ measurements (EUMETSAT 2019).

Coastal moorings will follow EMSO-ERIC & OceanSites QC protocols.

Glider inter-calibration techniques will follow the recommendations of EURO-ARGO ERIC (e.g. O2, Chla).

Data management issues: The validity of ocean colour algorithms in turbid and highly absorbing coastal waters still represents an issue. This must be highlighted by ocean colour experts. A significant effort is still required to multiply quality matchups between satellite and in situ data in such waters, notably using autonomous field platforms.

Expected results: Validated ocean colour satellite products (water turbidity, concentrations of suspended particulate matter and chlorophyll-a with associated uncertainties). Harmonising approaches across the PSS will provide the synthesis for quantifying critical region-wide processes such as community and export production, nutrient cycling, ocean acidification, coastal eutrophication, and pollution.

Users of results: Persons in charge of water quality monitoring based on in situ field sampling and scientists in charge of biogeochemical models and in situ observations (eg. time series)

Dissemination of results: during regional/MONGOOS workshops and annual JERICO-S3 meetings

Links: T2.4 to improve connectivity and identifying the gaps, WP5 & WP6 to elaborate best practices on BGC variables and QC procedures.