Earth Observation products for Science and Innovation in the Black Sea

The Black Sea is a small enclosed basin where coastal regions have a large influence and mesoscale signals dominate the dynamics (the Rossby radius of deformation is about 20km). Large riverine inputs, mainly on the northwestern shelf, induce well-marked horizontal gradients in the distribution of the Black Sea salinity and optical characteristics: coastal and shelf waters have very low salinity and contain large amounts of optically active materials (e.g. coloured dissolved organic matter) and its oligotrophic deep sea has a salinity around 18.2. The presence of these contrasting water characteristics in a relatively small enclosed environment, combined with land contamination and the specificities of its atmospheric composition(e.g. high cloud coverage, aerosols) make the Black Sea a challenging area for the development of high quality satellite products. 

 

We present first results from a 2-year on-going ESA-funded project, EO4SIBS (Earth Observation for Science and Innovation in the Black Sea) dedicated to the development, and subsequent scientific analysis, of new algorithms and products. In particular, ocean colour products (chlorophyll-a and total suspended matter concentrations, turbidity) were produced from Sentinel 3 (S3) OLCI data combining different algorithms selected based on an automatic water mass classification procedure (case-1 versus case-2 waters). In specific areas, S3-OLCI and Sentinel 2-MSI data were merged to address local features. A revised gridded altimetry product based on 5-Hz along track data (combining Cryosat and S3 SAR) was produced and validated in the coastal zone with tide gauge data. Sea Surface Salinity was derived from the L-Band measured by SMOS and compared with in-situ surface salinity data from field sampling and Argo. 

 

All these products are now being integrated to further understand the Black Sea physical and biogeochemical functioning (e.g., plume and productivity patterns, mesoscale dynamics, deoxygenation). For instance, the Black Sea mesoscale dynamics are inferred from the 5-Hz altimetry product using an eddy detection and tracking algorithm. The quality of the eddy mapping is assessed by comparison with visible and infrared satellite products while the derived velocities are compared with drifters. Also, the benefit of assimilating ocean colour data in the Black Sea operational model (also known as CMEMS BS-MFC BIO) for the prediction of the Black Sea ecosystem will  be illustrated.

 

Gridded products are archived as CF-compliant NetCDF files and disseminated through ncWMS protocol. In-situ data are modeled as vector points in a PostGIS database. A web portal is being implemented in order to propose an efficient spatiotemporal exploration of both data sources in a user-friendly interface, including interactive map layers and export possibilities.

 

We conclude with a set of recommendations for observational requirements needed  to increase the quality of satellite products in the Black Sea and to be able to use the full potential of current and new information provided by  satellites.