The data collection of the North Sea is divided in two datasets : the discrete collection and the trajectories collection. The Discrete SeaDataCloud Temperature and Salinity Historical Data Collection for the North Sea includes open access in situ data on temperature and salinity measured with “discrete” instruments (CTD, XBT, discrete water samplers…). The data span between 4°W and 10°E in longitude, and from 49°N to 62°N in latitude. It covers the time period 1893 – 2017. The data were retrieved from the SeaDataNet infrastructure in November 2017. The “Trajectories” SeaDataCloud Temperature and Salinity Historical Data Collection for the North Sea includes open access in situ data on temperature and salinity measured by continuously recording sensors (e.g. Ferryboxes). The data span between 4°W and 10°E in longitude, and from 49°N to 62°N in latitude. It covers the time period 1989 – 2017. The data were retrieved from the SeaDataNet infrastructure in November 2017. The quality control of the data has been performed with the help of ODV software. Data Quality Flags have been revised following common recommended procedures defined under SeaDataNet 2 project in conjunction with visual expert check. The dataset format is ODV binary collections. You can read, analyse and export from the ODV application provided by Alfred Wegener institute at http://odv.awi.de/. For data access please register at http://www.marine-id.org/.

Combined product of Water body chlorophyll a based on DIVA 4D 10-year analysis on five regions : Northeast Atlantic Ocean, North Sea, Baltic Sea, Black Sea, Mediterranean Sea. The boundaries and overlapping zones between these five regions were filtered to avoid any unrealistic spatial discontinuities. This combined Water body chlorophyll a product is masked using the relative error threshold 0.5. Units: mg/m^3. Created by 'University of Liege, GeoHydrodynamics and Environment Research (ULg-GHER)'.

The analysis was performed per season using DIVA software tool (Data-Interpolating Variational Analysis). The analyses products are stored as NetCDF CF files and made available as WMS layers for easy browsing and adding. Every step of the time dimension corresponds to a 6-year moving average from 1983 to 2016. The depth dimension spans from surface to 1000 m, with 21 vertical levels. The boundaries and overlapping zones between these regions were filtered to avoid any unrealistic spatial discontinuities. This combined water body dissolved oxygen concentration product is masked using the relative error threshold 0.5. Units: µmol/l Created by 'University of Liège, GeoHydrodynamics and Environment Research (ULiège-GHER)'. The data used as input for DIVA have been extracted from the EMODnet Chemistry Download Service: https://emodnet-chemistry.maris.nl/search Intermediate regional data products: Mediterranean Sea - DIVA 4D 6-year analysis of Water body chlorophyll-a 1990/2017 v2018 https://doi.org/10.6092/5346c32c-acd3-4534-800a-7947f5914315 Arctic Ocean - DIVA 4D 6-year analysis of Water body chlorophyll-a 1980/2017 v2018 https://doi.org/10.6092/28a025c3-1f79-4f6d-b71a-86641e2b7346 Black Sea - DIVA 4D 6-year analysis of Water body chlorophyll-a 1990/2016 v2018 https://doi.org/10.6092/3da98812-0b51-40ca-a95b-3f43de243c74 North East Atlantic Ocean - DIVA 4D 6-year analysis of Water body chlorophyll-a 1960/2017 v2018 https://doi.org/10.6092/ce474bda-7eba-11e8-84a3-40a8f051e8d0 North Sea - DIVA 4D 6-year analysis of Water body chlorophyll-a 1980/2017 v2018 https://doi.org/10.6092/d0e36bce-91d2-4baf-996d-2be3e16164f1 Baltic Sea - DIVA 4D 6-year analysis of Water body chlorophyll-a 1980/2016 v2018 https://doi.org/10.6092/66dcf80f-383c-4c70-842a-80eead8bd293