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 silicate 1965/2016 v2018 https://doi.org/10.6092/bb4fa82c-7731-4b1d-9cde-a031ca83e40c Arctic Ocean - DIVA 4D 6-year analysis of Water body silicate 1980/2017 v2018 https://doi.org/10.6092/3ebe4a8b-9ecb-4e00-b617-47576d49dc29 North Sea - DIVA 4D 6-year analysis of Water body silicate 1980/2017 v2018 https://doi.org/10.6092/62eebfd8-f97f-4e28-9e2e-9677a3b165ad Black Sea - DIVA 4D 6-year analysis of Water body silicate 1990/2016 v2018 https://doi.org/10.6092/9521c33f-d8d1-4576-b184-6651c1c0145b North East Atlantic Ocean - DIVA 4D 6-year analysis of Water body silicate 1971/2017 v2018 https://doi.org/10.6092/468fc3aa-139d-450f-afe2-a0dc81953533

Water body silicate - Seasonal Climatology for Gulf of Riga for the period 1994-2019 on the domain: Lon 22.3-25.0°E, Lat 56.8-58.4°N. Data Sources: observational data from SeaDataNet/EMODnet Chemistry Data Network. Description of DIVA analysis: The computation was done with the DIVAnd (Data-Interpolating Variational Analysis in n dimensions), version 2.7, using GEBCO 30sec topography for the spatial connectivity of water masses. Horizontal correlation length of 25 km and vertical correlation length of 10 m. Depth range: 0.0, 2.5, 5, 10, 15, 20, 25, 30, 40, 50 m. Units: µmol/l. The horizontal resolution of the produced DIVAnd maps grids is 0.01 degrees.

Moving 10-years analysis of Silicate at Northeast Atlantic Ocean for each season. - winter: January-March, - spring: April-June, - summer: July-September, - autumn: October-December Every year of the time dimension corresponds to the 10-year centred average of each season. Decades span - from 1963-1972 until 2005-2014 (winter) - from 1979-1988 until 2005-2014 (spring) - from 1990-1999 until 2005-2014 (summer) - from 1964-1973 until 2005-2014 (autumn) Observational data span from 1962 to 2014. Depth range (IODE standard depths): -3000.0, -2500.0, -2000.0, -1750, -1500.0, -1400.0, -1300.0, -1200.0, -1100.0, -1000.0, -900.0, -800.0, -700.0, -600.0, -500.0, -400.0, -300.0, -250.0, -200.0, -150.0, -125.0, -100.0, -75.0, -50.0,-40.0, -30.0, -20.0, -10.0, -5.0, -0.0 Data Sources: observational data from SeaDataNet/EMODNet Chemistry Data Network. Description of DIVA analysis: Geostatistical data analysis by DIVA (Data-Interpolating Variational Analysis) tool. GEBCO 1min topography is used for the contouring preparation. Analyzed filed masked using relative error threshold 0.3 and 0.5 DIVA settings. Signal to noise ratio and correlation length were optimized and filtered vertically and a seasonally-averaged profile was used. Logarithmic transformation applied to the data prior to the analysis. Background field: the data mean value is subtracted from the data. Detrending of data: no, Advection consraint applied: no. Units: umol/l

Water body silicate - Seasonal Climatology for Danube Delta (NW Black Sea) for the period 1970-2018 on the domain: Lon E28.5-30.5°E, Lat N43.7-45.6°N. (winter: December-February, - spring: March-May, - summer: June-August, - autumn: September-November). Data Sources: observational data from SeaDataNet/EMODNet Chemistry Data Network. Description of DIVA analysis: The computation was done with the DIVAnd (Data-Interpolating Variational Analysis in n dimensions), version 2.7.5, using GEBCO 30sec topography for the spatial connectivity of water masses. Horizontal correlation length of 47.730km and vertical correlation length of 45m were applied. Depth range: 0, 2.0, 4.0, 6.0, 8.0, 10.0, 15.0, 20.0, 25.0, 30.0, 40.0, 50.0 m. Units: umol/l. The horizontal resolution of the produced DIVAnd maps grids is 0.01 degrees.

Water body silicate - Seasonal Climatology for Po River for the period 1980-2019 on the domain: Lon E12.0-14.0 deg.E, Lat N44.0-46.00 deg.N. Data Sources: observational data from SeaDataNet/EMODNet Chemistry Data Network. Description of DIVA analysis: The computation was done with the DIVAnd (Data-Interpolating Variational Analysis in n dimensions), version 2.7.4, using GEBCO 30sec topography for the spatial connectivity of water masses. A relative correlation length used based on topography gradients and the horizontal correlation length varies from 25 km to 12.5 km. The vertical correlation length (in meters) is: [4.,4.,4.,4.,4.,10.,10.,10.,10.,20.,20.,20.,20.,20.]. Depth range: [0., 2., 4., 6., 8., 10., 15., 20., 25., 30., 40., 50., 60., 70.]. Units: umol/l. The horizontal resolution of the produced DIVAnd maps grids is dx=dy=0.009 degrees (around 975m and 708m accordingly). Additional analysis parameters: The error variance (epsilon2) was set equal to 1. Data weight was reduced near the coasts. Data weighting was applied with the following threshold values: lon=0.03, lat=0.03, depth=2. Threshold value for log transformation=200. Seasons definition: Winter=Jan-Mar, Spring=Apr-Jun, Summer=Jul-Sep, Autumn=Oct-Dec. DOI: 10.6092/njvc-n987

Moving 6-year analysis of Water_body_silicate in the Black Sea for each season: spring (March-May), summer (June-August), autumn (September-November), winter (December-February). Every year of the time dimension corresponds to the 6-years centred average of each season. 6-years periods span: from 1970-1975 until 2013-2018 Depth range (IODE standard depths): -200.0, -150.0, -125.0, -100.0, -75.0, -50.0,-40.0, -30.0, -20.0, -10.0, -5.0, -0.0. Data Sources: observational data from SeaDataNet/EMODnet Chemistry Data Network. Description of DIVA analysis: Geostatistical data analysis by DIVA (Data-Interpolating Variational Analysis) tool. GEBCO 1min topography is used for the contouring preparation. Analysed field masked using relative error threshold 0.3 and 0.5 DIVA settings: signal-to-noise ratio and correlation length were estimated using data mean distance as a minimum (for L) and vertically filtered. Log transformation was used in the analyses. Background field: the data mean value is subtracted from the data. Detrending of data: no, Advection constraint applied: no. Units: umol/l. The entire set of related maps can be found in the viewing service: http://ec.oceanbrowser.net/emodnet/

This gridded product visualizes 1960 - 2014 water body silicate concentration (umol/l) in the North Sea domain, for each season (winter: December – February; spring: March – May; summer: June – August; autumn: September – November). It is produced as a Diva 4D analysis, version 4.6.9: a reference field of all seasonal data between 1960-2014 was used; results were logit transformed to avoid negative/underestimated values in the interpolated results; error threshold masks L1 (0.3) and L2 (0.5) are included as well as the unmasked field. Every step of the time dimension corresponds to a 10-year moving average for each season. The depth dimension allows visualizing the gridded field at various depths.

Moving 6-year analysis of Water body silicate in the Arctic Ocean, for each season in the period 1965-2017. Every year of the time dimension corresponds to the 6-year centered average for each season. Winter: December-February, Spring: March-May, Summer: June-August, Autumn: September-November. Depth range (IODE standard depths): 0, 5, 10, 20, 30, 40, 50, 75, 100, 125, 150, 200, 250, 300, 400, ..., 1500, 1750, 2000, 2500m. Units: umol/l. Description of DIVA analysis: The computation was done with the DIVAnd (Data-Interpolating Variational Analysis in n dimensions), version 2.6.6, using GEBCO 30sec topography for the spatial connectivity of water masses. The horizontal resolution of the produced DIVAnd maps grids is 0.1 degrees. Signal-to-noise ratio was fixed to 2.0, horizontal correlation length to 100 km, and vertical correlation length varying between 25 and 200 m. Logarithmic transformation is applied to the data prior to the analysis. Background field: the data mean value is subtracted from the data.

Moving 6-year analysis of Water_body_silicate in the Mediterranean Sea for each season: - winter: January-March, - spring: April-June, - summer: July-September, - autumn: October-December. Every year of the time dimension corresponds to the 6-year centered average of the season. 6-years periods span from 1965-1970 until 2014-2019. Observational data span from 1960 to 2019. Depth range (IODE standard depths): 1500.0, 1400.0, 1300.0, 1200.0, -1100.0, -1000.0, -900.0, -800.0, -700.0, -600.0, -500.0, -400.0, -300.0, -250.0, -200.0, -150.0, -125.0, -100.0, -75.0, -50.0, -30.0, -20.0, -10.0, -5.0, -0.0. Data Sources: observational data from SeaDataNet/EMODnet Chemistry Data Network. Description of DIVA analysis: Geostatistical data analysis by DIVA (Data-Interpolating Variational Analysis) tool. Profiles were interpolated at standard depths using weighted parabolic interpolation algorithm (Reiniger and Ross, 1968). GEBCO 1min topography is used for the contouring preparation. Analysed filed masked using relative error threshold 0.3 and 0.5. DIVA settings: A constant value for signal-to-noise ratio was used equal to 1. Correlation length was optimized and filtered vertically and a seasonally-averaged profile was used. 'log(data)-exp(analysis' transformation applied to the data prior to the analysis. Background field: the data mean value is subtracted from the data. Detrending of data: no. Advection constraint applied: no. Units: umol/l. The entire set of related maps can be found in the viewing service: http://ec.oceanbrowser.net/emodnet/ . Originators of Italian data sets-List of contributors: - Brunetti Fabio (OGS) - Cardin Vanessa, Bensi Manuel doi:10.6092/36728450-4296-4e6a-967d-d5b6da55f306 - Cardin Vanessa, Bensi Manuel, Ursella Laura, Siena Giuseppe doi:10.6092/f8e6d18e-f877-4aa5-a983-a03b06ccb987 - Cataletto Bruno (OGS) - Cinzia Comici Cinzia (OGS) - Civitarese Giuseppe (OGS) - DeVittor Cinzia (OGS) - Giani Michele (OGS) - Kovacevic Vedrana (OGS) - Mosetti Renzo (OGS) - Solidoro C.,Beran A.,Cataletto B.,Celussi M.,Cibic T.,Comici C.,Del Negro P.,De Vittor C.,Minocci M.,Monti M.,Fabbro C.,Falconi C.,Franzo A.,Libralato S.,Lipizer M.,Negussanti J.S.,Russel H.,Valli G., doi:10.6092/e5518899-b914-43b0-8139-023718aa63f5 - Celio Massimo (ARPA FVG) - Malaguti Antonella (ENEA) - Fonda Umani Serena (UNITS) - Bignami Francesco (ISAC/CNR) - Boldrini Alfredo (ISMAR/CNR) - Marini Mauro (ISMAR/CNR) - Miserocchi Stefano (ISMAR/CNR) - Zaccone Renata (IAMC/CNR) - Lavezza, R., Dubroca, L. F. C., Ludicone, D., Kress, N., Herut, B., Civitarese, G., Cruzado, A., Lefèvre, D., Souvermezoglou, E., Yilmaz, A., Tugrul, S., and Ribera d'Alcala, M.: Compilation of quality controlled nutrient profiles from the Mediterranean Sea, doi:10.1594/PANGAEA.771907, 2011.

Moving 6-year analysis of Silicate at Atlantic Sea for each season. - winter: January-March, - spring: April-June, - summer: July-September, - autumn: October-December Every year of the time dimension corresponds to the 6-year centred average of each season. 6-year periods span - from 1972-1977 until 2015-2020 (winter), - from 1984-1989 until 2015-2020 (spring), - from 1972-1977 until 2015-2020 (summer), - from 1971-1976 until 2015-2020 (autumn). Observational data span from 1971 to 2020. Depth range (IODE standard depths): -2000.0, -1750, -1500.0, -1400.0, -1300.0, -1200.0, -1100.0, -1000.0, -900.0, -800.0, -700.0, -600.0, -500.0, -400.0, -300.0, -250.0, -200.0, -150.0, -125.0, -100.0, -75.0, -50.0,-40.0, -30.0, -20.0, -10.0, -5.0, -0.0 Data Sources: observational data from SeaDataNet/EMODNet Chemistry Data Network. Description of DIVA analysis: Geostatistical data analysis by DIVA (Data-Interpolating Variational Analysis) tool. GEBCO 1min topography is used for the contouring preparation. Analyzed filed masked using relative error threshold 0.3 and 0.5 DIVA settings. Correlation length was optimized and filtered vertically and a seasonally-averaged profile was used. Signal to noise ratio was fixed to 1. Logarithmic transformation applied to the data prior to the analysis. Background field: the data mean value is subtracted from the data. Detrending of data: no, Advection constraint applied: no. Units: umol/l