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.

Regional hunting numbers for Ringed seals 2011-2014.

Regional hunting numbers for Harbour seals 2011-2014.

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

Polluting ship accidents is based on reporting of shipping accidents done by HELCOM Contracting Parties to produce annual within HELCOM MARITIME group. Data were available for 2016-2020. Attribute specifications and units Country Year Date__dd_m: Date (dd.mm.yyyy) Time__hh_m: Time (hh:mm) Latitude: Latitude (decimal degrees) Longitude: Longitude (decimal degrees) Location Ship_1_nam: Ship 1 name, flag Sh1_Categ: Ship 1 type (according to AIS category) Sh1_Type: Details of ship 1 type Sh1_Hull: Hull type (ship 1) Sh1Size_gt: Size (gt) (ship 1) Sh1Sezidwt: Size (dwt) (ship 1) Sh1Draug_m: Draught (m) (ship 1) Ship2_Name: Ship 2 name, flag Sh2_Categ: Shiptype 2 (according to AIS category) Sh2_Type: Details of ship 2 type Sh2_Hull: Hull type (ship 2) Sh1Size_gt: Size (gt) (ship 2) Sh2Sizedwt: Size (dwt) (ship 2) Sh2Draug_m: Draught (m) (ship 2) Cargo_Type Acc_Type Colli_Type Acc_Detail Cause_Sh1 Cause_Sh2 HumanEleme IceCondit CrewIceTra CauseDetail Pilot_Sh1 Pilot_Sh2 Offence Damage Assistance Pollution Pollu_m3 Pollut_t Pollu_Type RespAction Add_Info version F44 original_a original_l original_s original_c

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.

The dataset contains total landings of herring 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 fishing intensity map displays data provided in C-square (0.05 x 0.05 degrees) converted to 1x1 km raster 2011-2016. The value of raster cell is subsurface swept area ratio. The data does not cover Russian waters.

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: More info: http://www.helcom.fi/helcom-at-work/projects/completed-projects/balthazar/hazardous-waste