Input of impulsive anthropogenic sound includes impulsive events from 2016-2021

• Seismic surveys (HELCOM-OSPAR Registry; national data call submissions as lines in the folder of data)

• Explosions (HELCOM-OSPAR Registry)

• Pile driving (HELCOM-OSPAR Registry)

• Airguns (HELCOM-OSPAR Registry)

For the different event types, numeric intensity value was used to represent the pressure as categorized in HELCOM-OSPAR Impulsive noise registry. All nationally reported seismic surveys were given intensity values “Very low” (0.25)

- Very low (0.25)

- Low (0.5)

- Medium (0.75)

- High (1)

The impact distance has not been taken into account due to the different nature of separate datasets used for the pressure layer. We acknowledge that e.g. pile driving and airguns may impact up to 20 km from the source event. The spread of the sound wave depends on the sound frequency, water salinity, temperature and density.