Chemistry

Data & products on marine water quality

How are products generated

The harmonised, standardized and validated data collections have been used to generate the related products, by means of different methods and technologies as described hereafter.

Eutrophication

Gridded climatologies

These products have been generated with the Data-Interpolating Variational Analysis (DIVA) method by using the DIVA and DIVAnd softwares. These tools allow to spatially interpolate sparse and irregularly distributed in situ observations on a regular grid. Additionally, they allow to compute error maps for the gridded fields, which reflect accuracy and distribution of the observations, and are fundamental to assess the reliability of the gridded fields. DIVAnd (Data-Interpolating Variational Analysis in n dimensions) performs an n-dimensional variational analysis/gridding of arbitrarily located observations. The latter will be interpolated/analyzed on a curvilinear grid in 1, 2, 3 or more dimensions. In this sense DIVAnd is the generalization in n dimensions (lon, lat, depth, time, etc.) of the original two-dimensional DIVA version not further developed anymore. It is written in Julia language, which is fast, dynamic, easy-to-learn & install. (Barth et al. (2014). DIVAnd-1.0: n-dimensional variational data analysis for ocean observations).
The products are combined DIVA analysis of each variable concentration masked using the relative error threshold 0.5, specifically: 1. monthly climatologies for all European Seas combined data, 2. seasonal maps by sea Region, and 3. seasonal maps for specific coastal areas. The boundaries and overlapping zones between regions were filtered to avoid any unrealistic spatial discontinuities.

The detailed methodology is described in the User Manual for regional climatologies with DIVA.

Contaminants

Spatial distribution and MSFD focused data evaluation

EMODnet Chemistry makes available maps regarding Anthracene, Benzo[A]pyrene, Fluoranthene, Hexachlorobenzene, Naphthalene, DDT, Lead, Mercury, Cadmium, and Tributyltin. Contaminant products have been developed according to the primary criteria D8C1 of the Marine Strategy Framework Directive (Directive 2008/56/EC). In particular, they are focused on the requirements under the Commission Decision 2017/848, laying down criteria and methodological standards on good environmental status of marine waters, and specifications and methods for monitoring and assessment. The use of a geo database has allowed to make the necessary queries for the production of the maps based on the matching criteria.

The detailed methodology is described in the Proposal for generating dedicated maps on contaminants.

Marine Litter

Spatial distribution, composition and abundance

The harmonization of all the data has been the most challenging task considering the heterogeneity of the data sources, sampling protocols and reference lists used on a European scale.
Concerning beach litter, many preliminary processing were necessary to harmonize all the data: selection of protocols, separation of monitoring surveys from research and cleaning operations, normalization processes, removal of some categories and some litter types etc.
Concerning seafloor litter, the preliminary processing had to take into account that within the same protocol, different gear types are deployed during fishing bottom trawl surveys.

The detailed methodology is described in the Guidelines and forms for gathering marine litter data.

Map Viewer

The EMODnet Chemistry products visualization is possible thanks to a python WSGI server software implementing the Web Map Service (WMS) protocol. This web server is based on open standards from the Open Geospatial Consortium (OGC), in particular WMS and Web Feature Service (WFS). These standards define a protocol for describing, requesting and querying two-dimensional maps at a given depth and time.

Catalogue service

Ifremer developed the Catalogue service software which is based on open source GeoNetwork. The catalogue offers search filters adapted to EMODnet Chemistry, and provides CSW endpoint which is used for harvesting into catalogues of other portals. Each data product record provides Inspire-compliant description, view and download link: access to layers in Map viewer, OPeNDAP service (for gridded products), portal DOI landing pages,and direct download links.

webODV data Explorer and Extractor

The new webODV online tool provides fast and easy access to data collections concerning eutrophication, ocean acidification and contaminants. The data explorer allows ODV-like interactive analysis and visualization of the data. The webODV data extractor allows users to subset the EMODnet Chemistry aggregated datasets in many different ways and to extract these data subsets in a variety of formats. The webODV data explorer allows users to create different kinds of graphics and products with ODV-online.