Ocean Color and Sea Surface Temperature

With global population expansion, the demand for high-quality protein is rising dramatically, and fish farming is gaining importance to ensure food security. Aquaculture is the fastest growing food production sector worldwide. Environmental conditions determine the growth and health of the produced species, while the production often releases large amounts of nutrients to the surrounding environment. In particular, harmful algal blooms are a major threat to aquaculture production.

To support the growth of efficient and sustainable aquaculture production, the FP7 project AQUA-USERS aims at providing the aquaculture industry with user-relevant and timely information based on the most up-to-date satellite data and innovative optical in-situ measurements. The key purpose is to develop a web portal and mobile application that bring together satellite information on water quality and temperature with in-situ observations as well as relevant weather prediction and met-ocean data. A decision support system underlying the applications links this information to a set of user-determined management decisions.

AQUA-USERS is a highly user-driven project with a user board consisting of companies and organisations from 5 countries representing different European aquaculture production systems. Together with the user board, the project partners are demonstrating the applicability of the developed methods and tools in several case studies.

The first phase of the project concentrated on user requirements, method development and technical preparation and implementation. Particular focus was on developing new and improved methods for making EO data useful for the aquaculture industry. For the study areas, a full archive of MERIS full resolution data has been processed with regionally adapted and validated algorithms for water quality parameter retrieval. Together with an archive of sea surface temperature data based on a number of different sensors, these data sets are used as a basis for site characterisation and selection.

Based on satellite and in-situ data, a method has been established to derive indicators for potential benefits and risks for aquaculture production. Where available, also biogeochemical parameters were included in the analysis. Regarding the detection of harmful algal blooms with optical methods, two approaches have been pursued: training a detection algorithm with spectra of known blooms of certain species on multi-spectral satellite images, and modelling of hyperspectral HAB data based on laboratory experiments on cultures of these species.

The AQUA-USERS consortium already addressed site characterisation and selection based on historic satellite data. For areas of potential new aquaculture sites, physical, chemical and biological indicators relevant for the optimal operation were collected from Earth observation and physical models. These data were classified according to suitability for specific species and regions. The resulting suitability maps were combined with administrative constraints to yield maps highlighting the most promising areas for the implementation of new aquaculture sites.

In the next phase of the project, we will bring together the tools and methods developed within AQUA-USERS for operational management. Via the AQUA-USERS app and web portal, users will be able to access near real-time EO data, in-situ measurements and relevant met-ocean data from external sources. Based on these up-to-date measurements and indicators on how they relate to long-term averages and to critical production thresholds, better-informed management decisions can be taken by the users. The decisions the users make are recorded along with the information they were based on for further analysis, evaluation and improvements.

AQUA-USERS is focusing its approach on tailoring methods to the specific requirements of the different aquaculture sectors and the diverse regions with contrasting environmental conditions. This approach should facilitate uptake of the services by the European aquaculture sector and thus support this industry in making their production more efficient. Therefore, AQUA-USERS will contribute to a more sustainable management of marine resources in Europe.

The ESA ocean heat flux project aims to better understand and quantify ocean heat fluxes through the use of satellite and in situ data and model analyses.One aspect of this work includes using satellite ocean colour data, optical models and ocean turbulence models to investigate the impact of light penetration on upper ocean dynamics and heat fluxes. Sensitivity tests were designed using an optical model to force a general ocean turbulence model. From these tests, changes in temperature throughout the water column and surface heat fluxes as a result of variable chlorophyll-a concentration, were quantified. This sensitivity was placed in context with further experiments under various seasonal and wind conditions. Using the same optical model, maps of light penetration, relative to the mixed layer depth, were generated based on satellite data from the ocean colour climate change initiative (OC-CCI).

The Bay of Bengal is a strongly stratified tropical basin experiencing seasonal monsoonal climate. The strong stratification arising due to the huge fresh water runoff from rivers bordering the Bay of Bengal as well as the large quantities of precipitation curtails the wind-driven mixing. This combined with light limitation during summer monsoon in the northern Bay of Bengal makes the upper water column a region of low chlorophyll biomass. Using 10-years of sediment trap data, in situ co-located physical and biogeochemical data and satellite-derives remote sensing data we show that the organic carbon production in the Bay of Bengal is strongly  influenced by the meso-scale eddies and propagating planetary waves, in the absence of any strong and sustained upwelling. Further we show that the eddy-pimping of nutrients to the oligotrophic upper waters mediated by the cold-core cyclonic eddies alters phytoplankton composition from cocolithophore-dominated ecosystem towards diatom-dominated ecosystem. This has implication to sinking carbon as well as out-gassing of CO₂ thereby influencing regional CO₂ balance. Finally, we show that an increased warming as well as stratification of the upper waters of the Bay of Bengal has the potential to reduce the chlorophyll biomass, while the projected increase in the cyclone frequency and intensity under warming scenario would enhance the upper ocean chlorophyll biomass.

The FP7/HIGHROC (“HIGH spatial and temporal Resolution Ocean Colour”) Project is developing the next generation of optical products for coastal water services. These products are based on both mainstream ocean colour sensors (Sentinel-3/OLCI, VIIRS) and other satellite missions such as the meteorological MSG/SEVIRI sensors and the land-oriented Landsat-8 (L8) and Sentinel-2 (S2) missions. SEVIRI gives data every 15 minutes from a geostationary orbit, offering much better temporal coverage in periods of scattered clouds and the possibility to follow diurnal and tidal processes in cloud-free periods, albeit at reduced spatial resolution. S2 and L8 offer much better spatial resolution, down to 10m (S2), allowing detection of many human impacts invisible at 300m resolution, albeit with lower frequency of acquisition.

During the User Service Trials, to be carried out from Oct 2016 to Sep 2017, products from all these missions will be provided to a core user group covering a range of applications including: coastal water quality monitoring, e.g. the European Union Water Framework and Marine Strategy Framework Directives; Environmental Impact Assessment of activities and constructions at sea; sediment transport associated with offshore construction, sand extraction and dredging activities, etc.

In the build up to these User Service Trials the HIGHROC project is carrying out R&D activities to:

develop algorithms for processing water colour data (atmospheric correction, suspended particulate matter and chlorophyll a estimation, euphotic depth, etc.)

carry out in situ measurements, improve the methodologies for making such measurements and use these measurements for calibration and validation of algorithms and products

develop image processing chains to mass process data from all the relevant missions

Services based on these new products will be supplied to end-users in User Service Trial regions to further refine the products with the objective of providing long-term sustainable services.

This presentation will show some of the highlights of the project so far, including results from S2, L8 and SEVIRI.

Oceanic primary producers respond rapidly (within a few days) to a complex spectrum of climate-driven perturbations, confounding attempts to isolate the principal causes of observed changes. A dominant mode of variability in the Earth-climate system is that generated by the El Niño phenomenon. Recently, marked variations have been observed in the location of El Niño anomalous warming in the Equatorial Pacific, associated with two quite different alterations in environmental properties. Here, using observational and reanalysis datasets, we differentiate the regional physical forcing mechanisms and associated biological impacts caused by the two extremes types of El Niño. The sum of these regional effects integrated over the globe leads to phytoplankton biomass enhancement of +4.9% during the Central Pacific type of El Niño and reduction of -5.5% during the Eastern Pacific type of El Niño. Analysis of the dominant mechanisms forcing the biophysical interactions provides a guide to how the marine ecosystem might change in a warming climate.