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.

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.

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.

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.

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.

Processed atmospheric ceiling heights were recorded from a CT25K ceilometer. The instrument was mounted on the CCGS Amundsen icebreaker on the port side directly behind the ship's wheelhouse. Data were collected during transit, set transects, 24-hour stations, and multi-day drift stations. The instrument was running continuously during the IPY-CFL project, with only minor interruptions for maintenance activities.

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.

The dataset is composed of Ichthyoplankton and zooplankton captured during the ArcticNet cruise aboard the CCGS Amundsen from 2017 to 2019. Three samplers fitted with 200 µm to 500 µm mesh nets were used for zooplankton collection . One was a metallic structure with 4 nets of 1 square meter opening each (2x2 multiple net sampler) for water column integrated sampling pulled vertically over from 10 m above the bottom to the surface to catch mesozooplankton. The other sampler was 2 nets of 1 square meter opening each towed at 10 m depth for 20 minutes at 2 knots to catch ichthyoplankton and macrozooplankton. Finally, a 0.5 square meter opening multinet Hydrobios for stratified sampling into nine layer also hauled vertically from 10 m above the sea bottom to the surface. Zooplankton samples were preserved in a 10% buffered formalin seawater solution and were sieved through 1000 µm and 200 µm sieves for analysis. Ichthyoplankton was identified to the lowest taxonomic level possible, a sub-sample was measured and all larvea were kept in ethanol.

Processed atmospheric ceiling heights were recorded from a CT25K ceilometer. The instrument was mounted on the CCGS Amundsen icebreaker on the port side directly behind the ship's wheelhouse. Data were collected during transit, set transects, 24-hour stations, and multi-day drift stations. The instrument was running continuously during the project, with only minor interruptions for maintenance activities.

Processed atmospheric ceiling heights were recorded from a CT25K ceilometer. The instrument was mounted on the CCGS Amundsen icebreaker on the port side directly behind the ship's wheelhouse. Data were collected during transit, set transects, 24-hour stations, and multi-day drift stations. The instrument was running continuously during the IPY-CFL project, with only minor interruptions for maintenance activities.