10.1594/PANGAEA.995221Fischer, PhilippPhilippFischer0000-0002-3357-5420Alfred Wegener Institute - Biological Institute HelgolandLienkämper, MiriamMiriamLienkämperAlfred Wegener Institute - Biological Institute HelgolandBrand, MarkusMarkusBrand0000-0003-4768-1889Alfred Wegener Institute - Biological Institute HelgolandBussmann, IngeborgIngeborgBussmann0000-0002-1197-7461Alfred Wegener Institute - Biological Institute HelgolandBrix, HolgerHolgerBrix0000-0003-4229-6164Helmholtz-Zentrum HereonPANGAEA2026Alfred-Wegener-InstituteHereonin situ observationsMarGate underwater experimental areaMOSESObservatoryobservatory dataScientific divingCentre for Scientific Diving (CSD)Coastal Observing System for Northern and Arctic Seas (COSYNA)DAM mareXtreme - ElbeXtreme: Monitoring and modelling of extreme events in the Elbe estuary and the German Bight (ElbeXtreme)MarGate (MarGate)Modular Observation Solutions for Earth Systems (MOSES)Research Mission of the German Marine Research Alliance (DAM): Paths to improved risk management in the area of marine extreme events and natural hazards (mareXtreme)Shelf Seas Systems Ecology @ AWI (former Biologische Anstalt Helgoland) (BAH)2013-04-04T15:00:00/2024-12-31T23:00:00Publication Series of Datasets10.3389/fmars.2019.0003210.3389/fmars.2025.159900710.1007/978-3-030-30683-0_210.3389/fmars.2020.0055110.1038/s41598-025-05621-w10.3389/fmars.2021.77097710013/epic.06e24ad7-b885-4ff6-8dd7-99c0cda2580410.5194/os-13-259-201710.3390/jmse1303051610.1175/bams-d-20-0158.110.3389/fmars.2022.100215312 datasetsapplication/zipCreative Commons Attribution 4.0 InternationalThis dataset contains annual oceanographic observations collected at the Helgoland underwater observatory (54°11.594′ N, 07°52.762′ E; WGS84) from 2013 onwards. Measurements include water temperature, salinity, oxygen saturation, chlorophyll-a concentration, and turbidity. The observatory is located at a water depth of approximately 10 m (± tidal variation) and is equipped with one or more sensors for each measured parameter. Observations are recorded at an hourly temporal resolution. All data have undergone quality control using the four-step plausibility and quality assurance procedure described by Waldmann et al. (2022). The cabled observatory infrastructure and sensor configuration are described in detail on the AWI COSYNA underwater observatory webpage. For comprehensive information on instrumentation, sensor deployment, calibration procedures, and data processing, please refer to the annual metadata documents entitled metadata_heluwobs_yyyy_hydrography.pdf associated with each yearly dataset.7.86669999999999354.18330000000004Federal Ministry of Research, Technology and Spacehttps://doi.org/10.13039/50110000234703F0954BDAM mareXtreme - ElbeXtreme, AWIFederal Ministry of Research, Technology and Spacehttps://doi.org/10.13039/50110000234703F0954DDAM mareXtreme - ElbeXtreme, Hereon