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    This study presents sea surface concentrations of marine dimethylsulfide (DMS) measured across the Labrador Sea and the Canadian Arctic Archipelago during summer of 2017 (July-August). Using a novel automated instrument (ACT-MIMS) more than 2500 DMS observations were collected at high frequency alongside ancillary measurements of salinity, temperature, fluorescence (chlorophyll a proxy), solar radiation, ice concentration and the algal precursor of DMS, dimethylsulfoniopropionate. DMS concentrations ranged from ca. 1 to 32 nmol L-1 (average of 6 nmol L-1) in 2017 over an area covering a wide range of contrasting marine environments from coastal to open ocean, ice-free waters, as well as under-ice waters. Surface water DMS hotspots were measured in association with thermohaline oceanographic features in high productivity coastal waters, as well as with the presence of ponded first-year ice (FYI). Nighttime increases and daytime decreases of DMS concentrations were also observed in productive areas of the Labrador Sea and Davis Strait continental shelf. The association of DMS concentrations with diurnal solar radiation variation suggests the involvement of photobiological processes. Overall, our results strengthen the view that aqueous DMS cycling in the Arctic is intimately linked with sea ice dynamics and physiological responses to light. As such, future changes in the seasonality of the Arctic cryosphere will likely play an important role in shaping DMS emissions, although the sign and magnitude of the change remain highly uncertain.

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    The data set is composed of raw files recorded with the Kongsberg Maritime SX90 long-range, low frequency (20-30 kHz) fisheries sonar during the CCGS Amundsen 2013 summer expedition in the Eastern Canadian Arctic. The sonar transducer is lowered 2.5 feet below the hull through a gate-valve. The cylindrical 256-elements transducer allows both a horizontal and a vertical sound transmission, and the omni-directional (horizontal) sonar beam can be tilted from +10 to -60 degrees to scan a large portion of the water column. The raw acoustic data were saved onto an external drive and print screens of interesting targets (fish schools) were recorded.

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    The navigation data of the Amundsen scientific expeditions between 2003 and 2019 were recorded with the Position and Orientation Systems for Marine Vessels (POS-MV) and C-Nav Differential Global Navigation Satellite System (DGNSS) Precise Point Positioning systems. Two sets of controlled data are provided for each year of expedition. The first set is at time intervals of seconds for every day of the cruise and the second set is at 15 minute intervals. The data consist of Latitude, Longitude, Heading, Roll, Pitch, Heave, Track, Speed and Global Positioning System (GPS) sources at the second time intervals. The vessel's tracks in .kml (Google Earth format) were derived from the 15 minute time intervals dataset and are also provided. Research programs participating in the Amundsen expeditions between 2003 and 2017 were CASES, ArcticNet, IPY-CFL, Solas, Geotraces, Malina, IOL and BP, Jamstec, Netcare, Weston, BREA, iBO and GreenEdge.

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    Real-time atmospheric measurements were made on board the CCGS Amundsen. Sampling lines were placed on the forward mast of the ship, and instruments were housed in a sampling shed located on the top deck. Mixing ratios of volatile organic compounds (VOCs: dimethylsulfide, acetone, methanol, benzene, etc.) were measured using proton-transfer-reaction mass spectrometry. Aerosol size distributions between 10 and 500 nm were measured using a scanning mobility particle sizer and total aerosol number concentrations > 3 nm were measured using an ultrafine condensation particle counter. All data have time resolution of minutes.

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    Unfiltered aqueous total and methyl mercury concentrations were measured from water collection on board the NGCC/CCGS Amundsen at stations within the Beaufort Sea, Amundsen Gulf, and the Canadian Arctic Archipelago. Profiles of 10-12 m depth resolution were collected from 15 stations using the ship rosette system. Total mercury samples were analyzed on board. Methylmercury samples were preserved and transported to Winnipeg for analysis. Interpretation of results will also rely on supporting data from ArcticNet collaborators to identify water masses and determine biological productivity that determine the relative importance of external sources and internal cycling.

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    During the ArcticNet annual cruises of the research icebreaker CCGS Amundsen, characteristics of the near-surface atmosphere (basic meteorological elements, incident radiation) are monitored. Central to this integrated dataset, the following meteorological variables were recorded at 1 minute intervals (instrument used to collect each variable is in parentheses, and approximate instrument height above surface is indicated): wind speed (RM Young Wind Monitor 05106-10) - 16m height; wind direction (RM Young Wind Monitor 05106-10) -16m height; air temperature (Vaisala HMP45C) - 15m height; relative humidity (Vaisala HMP45C) -15m height; and, surface temperature (Apogee IR Transducer SI-111) - 8m height, atmospheric pressure. All instruments were mounted on a meteorological tower on the bow of the research icebreaker CCGS Amundsen, except for the IR transducer SI-111, which was mounted on top of the gunwale at the ship's bow, overlooking the water surface.

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    Microplastics pollution has been found across the globe, but with limited information from the polar regions. Although there is evidence of microplastics in the Arctic and Antarctic, little is understood about the sources, fate and extent of contamination. We collected samples and will quantify the amount and identify the types of microplastics in snow, ice, water, sediments and zooplankton sampled from the CCGS Amundsen in and around the Hudson Bay and/or the central and eastern Canadian Archipelago. In addition, we will answer questions about sources and fate using two types of information. We will examine patterns of microplastics contamination and compare them with land-use patterns and water and air circulation. Based on previous studies, and our preliminary findings, we believe that microplastics will be present in Arctic samples, but a detailed study will help us better understand how ubiquitous microplastics are, from where they are derived, and how they are preserved or degraded. Microplastics in the Arctic raise concerns about impacts to wildlife and local communities that rely on food from the sea. Results from this study will inform future experiments that answer questions related to such impacts.

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    The CCGS Amundsen is equipped with a RDI ADCP Ocean Surveyor (RDI os150), a ship-mounted current meter attached to the hull of the ship. The ship is also equipped of ice windows to protect the system while sailing through harsh arctic conditions. The current meter records continuous measures of the current along the ship transit route using a 150KHz sonar capable of covering the first 450m of the arctic water column. Since 2015 data are controlled using the Common Oceanographic Data Access System (CODAS, https://currents.soest.hawaii.edu/home/software/) of the University of Hawai'i, also adopted by the NOAA-National Centers for Environmental Information (NOAA-NCEI) to create the Joint Archive for Shipboard ADCP. Data are provided in NetCDF formats and follow the COARD (Cooperative Ocean/Atmosphere Research Data) convention. Detailed information and metadata are available in the documentation of the archive and in-built metadata files. Raw data since 2004 are available on demand.

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    Microplastics pollution has been found across the globe, but with limited information from the polar regions. Although there is evidence of microplastics in the Arctic and Antarctic, little is understood about the sources, fate and extent of contamination. We collected samples and will quantify the amount and identify the types of microplastics in snow (as a surrogate for air), water, sediments and zooplankton sampled from the CCGS Amundsen in and around the Hudson Bay and/or the central and eastern Canadian Archipelago. In addition, we will answer questions about sources and fate using two types of information. First, we will collaborate with an Indigenous community to quantify and type plastic along their shoreline. Second, we will examine patterns of microplastics contamination and compare them with land-use patterns and water and air circulation. Based on previous studies, and our preliminary findings, we believe that microplastics will be present in Arctic samples, but a detailed study will help us better understand how ubiquitous microplastics are, from where they are derived, and how they are preserved or degraded. Microplastics in the Arctic raise concerns about impacts to wildlife and local communities that rely on food from the sea. Results from this study will inform future experiments that answer questions related to such impacts.

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    The dataset is composed of adult fish species captured during the ArcticNet cruise aboard the CCGS Amundsen from 2017 to 2019. Pelagic fish were caught with an Isaacs-Kidd Midwater Trawl (IKMT, 9-m2 rectangular mouth aperture with mesh sizes of 11 mm in the first section and 5 mm in the last section). It was deployed from the surface to depths targeting possible aggregation of fish as recorded by the acoustic echosounder from the ship. Demersal and benthic fish were sampled with a bottom beam trawl (3-m2 rectangular aperture with a headline and a footrope of 4.27 m and a cod-end mesh of 9.5 mm) deployed on the seafloor. The pelagic and bottom trawls were towed at ~3 knots for 10 to 20 min. All fish collected by the trawls were measured and identified at least to the family level before freezing at -20°C.