This dataset is the first dedicated SMOS Sea Surface Salinity (SSS) product for the Baltic basin to enhance the science capabilities in the Baltic region and help to fill the gaps and grand challenges identified by the scientific community. These new product has been created under the funded ESA project ITT Baltic+ Salinity dynamics (4000126102/18/I-BG). This basin is one of the most challenging regions for the satellite SSS retrieval. The available EO-based SSS products are quite limited in terms of spatio-temporal coverage and quality. This is mainly due to technical limitations that strongly affect the brightness temperatures (TB), such as the high contamination by interferences and the contamination close to land and ice edges. Moreover, the sensitivity of TB to SSS changes is very low and dielectric models present limitations in this low salinity regime. Baltic+ L4 SSS product comprises 9 years (2011-2019) of daily maps at 0.05 degrees. A detailed explanation of the product algorithms and validation can be found at http://bec.icm.csic.es/doc/BEC_PD_SSS_Baltic_L3_L4.pdf and in the publication: Gonzalez-Gambau et al., “First SMOS Sea Surface Salinity dedicated products over the Baltic Sea“, Earth System Science Data, 2021 We present here the seasonal averaged Baltic+ L4 SSS products for the period 2011-2019. The daily Baltic+ L4 SSS products can be downloaded from the BEC FTP service (sftp://becftp.icm.csic.es) in the directory OCEAN/SSS/SMOS/Baltic/v1.0/L4/daily/

The availability of deep water habitat is based on the occurrence of H2S and describes the suitability of the bottom areas for the Baltic Sea biota, with regard to oxygen conditions of the near-bottom waters. The data used to produce the layer was provided by the Leibniz-Institut für Ostseeforschung Warnemünde (IOW) for the years 2016-2021.

Eutrophication, caused by excess inputs of nutrients, is one of the main threats affecting the Baltic Sea marine environment. Nutrients enter the Baltic Sea as waterborne (riverine inputs from the catchment area and direct discharges from point and diffuse sources in coastal areas) and airborne (atmospheric deposition) inputs. In 2007 HELCOM adopted a nutrient reduction scheme which is based on maximum allowable nutrient inputs (MAI) to reach "good environmental status" and country-wise nutrient reduction targets (CART) to share the burden of reducing nutrient pollution to the sea (HELCOM Baltic Sea Action Plan). Monitoring of nutrient inputs to the sea is important for assessing progress of countries towards their CART and to evaluate the effectiveness of measures to reduce pollution. This dataset displays total normalized annual average phosphorus loading as produced for href="http://www.helcom.fi/baltic-sea-trends/indicators/inputs-of-nutrients-to-the-subbasins" target="_blank"> HELCOM Core indicator: Inputs of nutrients to the subbasins based on HELCOM PLC data. Green colour of PLC subbasin indicates that inputs during 2016 were lower than MAI, red colour when they were higher, while yellow indicates that when taking into account the statistical uncertainty of input data it is not possible to determine whether MAI was fulfilled. The dataset contains following attributes: Basin: Name of PLC Subbasin Maximum allowable nutrient input: Maximum allowable phosphorus input for the subbasin (tons/year) P input including statistical uncertainty 2016: the average normalized phosphorus input during 2016 (tonnes/year) including statistical uncertainty for the subbasin Input 2016 including stat. uncertainty in % of MAI: proportion of average normalized phosphorus input during 2016 compared to MAI Classification of achieving MAI: Classification of achieving MAI is given in colours: green=MAI fulfilled, yellow= fulfilment is not determined due to statistical uncertainty, and red=MAI not fulfilled.

The objective of the BALTHAZAR project has been to assess the potential sources of hazardous substances from landfills/dumping sites, to characterise their environmental risks and to develop measures to reduce the risks of run-off of hazardous substances from waste site to the Baltic Sea. More info: http://www.helcom.fi/helcom-at-work/projects/completed-projects/balthazar/hazardous-waste

'Availability of deep water habitat, based on occurrence of H2S' layer describes the suitability of the bottom areas for the Baltic Sea biota, with regard to oxygen conditions of the near bottom waters. The data used to produce the layer was received from Leibniz-Institut für Ostseeforschung Warnemünde (IOW): - areas (polygons) with hydrogen sulfide (H2S) based on point measurements and modelling. Five time periods / year, for years 2011-2016 (altogether 30 layers). The polygons were converted to raster layers in a way, that for each time period (6 years, 5 time periods each year), areas with H2S got a value 0, other areas got the value 1. All layers were summed, (representing 6 years, 5 time periods each year, maximum value 30) and data was normalised. For more detailed information on the data used, please see Feistel et al. 2016.

Polluting ship accidents is based on reporting of shipping accidents done by HELCOM Contracting Parties to produce annual within HELCOM MARITIME group. Data was available for 2011-2013

The dataset contains total landings of sprat for years 2011-2016 reported per ICES statistical rectangles (tonnes / ICES rectangle) under EU Joint Research Centre’s data collection framework for fisheries data. Russian data extracted from ICES annual reports.

The dataset contains total landings of cod for years 2011-2016 reported per ICES statistical rectangles (tonnes / ICES rectangle) under EU Joint Research Centre’s data collection framework for fisheries data. Russian data extracted from ICES annual reports.

Digitized from Mariners’ Routeing Guide Baltic Sea ISBN 978-3-89871-771-7 (http://www.helcom.dk/map/). The line features are divided in categories, indicated by the the ZONE_TYPE attribute: 0 - Deep water route areas; 1 - Deep water route center line; 4 - Recommended route center; 6 - Traffic separation line; and 7 - Traffic separation scheme.

Eutrophication, caused by excess input of nutrients, is one of the main threats affecting the Baltic Sea marine environment. Nutrients enter the Baltic Sea as waterborne (riverine inputs from the catchment area and direct discharges from point and diffuse sources in coastal areas) and airborne (atmospheric deposition) inputs. In 2007 HELCOM adopted a nutrient reduction scheme which is based on maximum allowable nutrient inputs (MAI) to reach "good environmental status" and country-wise nutrient reduction targets (CART) to share the burden of reducing nutrient pollution to the sea (HELCOM Baltic Sea Action Plan). Monitoring of nutrient inputs to the sea is important for assessing progress of countries towards their CART and to evaluate the effectiveness of measures to reduce pollution. This dataset displays nutrient loading as produced for http://www.helcom.fi/baltic-sea-trends/indicators/inputs-of-nutrients-to-the-subbasins HELCOM Core indicator: Inputs of nutrients to the subbasins based on HELCOM PLC data. Green colour of PLC subbasin indicates that inputs during 2016 were lower than MAI, red colour when they were higher, while yellow indicates that when taking into account the statistical uncertainty of input data it is not possible to determine whether MAI was fulfilled. The dataset contains following attributes: Basin: Name of PLC Subbasin Maximum allowable nutrient input: Maximum allowable nitrogen input for the subbasin (tons/year) N input including statistical uncertainty 2016: the average nitrogen input during 2016 including statistical uncertainty (tons/year) N input 2016 including statistical uncertainty in % of MAI: proportion of normalized nitrogen input during 2016 compared to MAI (%) Classification of achieving MAI: Classification of achieving MAI is given in colours: green=MAI fulfilled, yellow= fulfilment is not determined due to statistical uncertainty, and red=MAI not fulfilled.