Anhaus, Philipp; Katlein, Christian; Matero, Ilkka; Nicolaus, Marcel; Arndt, Stefanie; Krampe, Daniela; Lange, Benjamin Allen; Regnery, Julia; Rohde, Jan; Schiller, Martin; Ransby, Daniela (2023): Under-ice environment surveys using a remotely operated vehicle (ROV) during the MOSAiC expedition 2019/20 [dataset bibliography]. PANGAEA, https://doi.org/10.1594/PANGAEA.951077

This bibliography unites different data types collected by a remotely operated vehicle (ROV) underneath drifting sea ice during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition of the research vessel Polarstern (AWI, 2017) between November 2019 and September 2020 (Nicolaus et al., 2022). The observation class M500 ROV was manufactured by Ocean Modules AB (Åtvidaberg, Sweden) and is owned by the Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung (Bremerhaven, Germany). It was equipped with an extended multidisciplinary sensor payload. To investigate the under-ice light field and bio-optical properties, the ROV was equipped with hyperspectral radiometers, transmissometers and a triplet fluorometer. Oceanographic properties were recorded with a standard CTD package including sensors for dissolved oxygen, nitrate and pH. Single beam and multibeam sonar allowed for a three-dimensional mapping of the ice underside, while an acoustic current profiler measured relative water currents. In addition to different video and still cameras for visual documentation of the under-ice environment, the ROV was equipped with a hyperspectral imager. For sampling of the under-ice ecosystem, a suction sampling system and an under-ice plankton as well as a gypsum net were attached to the ROV. Data were collected for all seasons and for various sea-ice and surface conditions. All data are provided at their original temporal resolution and have a common GPS synchronized timestamp. All times are given in UTC. Horizontal position of the ROV was determined using a long baseline acoustic positioning system and is provided in a floe-fixed, relative coordinate system (X, Y) with the origin (X=0 m, Y=0 m) at the ROV access hole in the MOSAiC central observatory (CO). Operations were conducted in a 300 m radius around the hole. A one function manipulator in combination with the ROV's six degrees of freedom enabled deployment and recovery of equipment (e.g. sediment traps) underneath the ice cover. Details about the respective deployment conditions can be found in the respective cruise reports of MOSAiC. A technical description of the ROV can be found in Katlein et al. (2017). MATLAB codes used for processing the data are published on ZENODO (Anhaus et al., 2023).

The data will be described in a respective ROV data paper. When reusing the data, please refer to this data paper (Anhaus et al., in prep.) and the actual datasets listed below (Datasets listed in this bibliography). Please carefully read the comment section below and contact the author(s) before using the data.

This datasets contain version 1.0 QC data, but the data is not corrected or polished to every aspect. It can be used, but issues and pitfalls remain. Known issues are the following:

• The datasets include also data recorded at the surface, before and after the respected surveys (needed for metadata), e.g., in a tent

• Horizontal position (X,Y)

◦ Leg 1: Scale factors and offsets to successfully improve positions for surveys PS122_1_5_62_20191102_1 and PS122_1_6_16_20191105_1 were obtained by comparing positions of markers from the ROV and a terrestrial laser scanner (RIEGL). Scale factors and offsets for surveys PS122_1_6_31_20191106_1, PS122_1_6_118_20191110_1, PS122_1_7_18_20191112_1, PS122_1_7_55_20191113_1 are based on estimates but will be improved also using markers.

◦ Leg 4: Positions for surveys PS122_4_48_213_20200726_1 and PS122_4_49_105_20200728_1 are partly distorted probably due to usage of drifting transponder(s) or erroneous transponder position configuration. Retrieving suitable scale factors and offsets was not successful so far.

◦ Leg 5: probably due to drifting transponder(s). Retrieving suitable scale factors and offsets was not successful so far.

• GPCTD data missing

◦ For all surveys during Leg 1 (PS122_1*), the GPCTD (Sea-Bird) data is missing. Data collected by a portable CTD that was attached to the ROV will be added here instead.

• Incoming irradiance data missing

◦ For one survey during Leg 1 and two surveys during Leg 2, the incoming irradiance data as measured by a RAMSES hyper-spectral radiometer (TriOS) is missing. This data will be substituted by the incoming irradiance measured at the crow's nest of RV Polarstern

• Sensor depth

◦ Not all individual sensor depths were corrected for pitch and roll