Time-series data of physical & biological oceanography, nutrient biogeochemistry and molecular biology were obtained from mooring HG-IV-S-4 in the Fram Strait in August 2019 - June 2021 as part of the Helmholtz infrastructure program Frontiers in Arctic Marine Monitoring (FRAM) and the long-term monitoring program at AWI HAUSGARTEN. The mooring was deployed during RV POLARSTERN expedition PS121, and recovered during PS126. The attached archive contains raw data files of three Seabird SBE37 microcats (nominal depths: 18m, 23m, 47m; sampling interval 1h), two Seabird SBE56 temperature loggers (nominal depths: 28m, 38m; sampling interval 30s), one Wetlabs ECO Triplet fluorometer (nominal depth: 23m; sampling interval 2h) and one Wetlabs ECO PAR sensor (nominal depth: 23m; sampling interval 2h). One ISUS nitrate sensor (nominal depth: 23m) was flooded and no data is available. The mooring also included a McLane RAS water sampler (nominal depth: 23m) and a McLane PPS phytoplankton sampler (nominal depth: 25m). Auxiliary information such as sensor calibration sheets, mooring diagrams and schedule files are also provided, if applicable.

The file HG-IV-S-4.zip includes all available sensor raw data from mooring HG-IV-S-4. The structure of the unzipped folders is mooring->sensor/sampler type->serial number->instrument files. All instruments were synched to UTC before deployment, and the offset after the recovery is supplied in the respective instrument folder, if available. The archive also contains the sensor calibration sheets/files and relevant sampler schedule files, if available. Finally, mooring schematics are also attached as pdfs in the root folder.The authors are grateful to the captains, crews and technical/scientific staff of the expeditions PS121 and PS126 onboard RV Polarstern. Many individuals have contributed to the conception of the research, the preparation of the instruments, the deployment and recoveries, as well as to the retrieval of the data, which we greatly acknowledge. We acknowledge funding from the Helmholtz infrastructure program "Frontiers in Arctic Marine Monitoring", and the Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung.