DMSP and DMS water concentrations were determine at fixed depths and at selected stations (ArcticNet stations) along a transect beginning in the North Water Polynya, going through the Lancaster Sound and the Northwest Passage, and terminating in the Beaufort Sea. During transit time, near surface DMS measurements were conducted every 2 hours from the pumping system of the CCGS Amundsen. In all cases, DMSP and DMS measurements were done following the methods of Kiene and Slezak 2006 (Limnol. Oceanogr.: Methods 4: 80-95). At selected stations, DMSP and DMS microbial cycling was determined during onboard incubations following the 35S-DMSP protocol (Merzouk et al. 2006, Deep Sea Res. 53:2370-2383).

The CTD data was obtained during the 2010 ArcticNet scientific cruise #1003b. The data were collected from October 8 to 17, 2010, aboard the CCGS Amundsen. There were 27 casts associated to 18 stations, located in the Northwest Passage. The following parameters were measured: temperature, conductivity and pressure (with a Sea-Bird SBE-9plus), dissolved oxygen (Sea-Bird SBE-43), fluorescence (Seapoint chlorophyll fluorometer), CDOM (Wetlabs FL(RT)D), nitrate concentration (Satlantic MBARI-ISUS 5T), transmittance (Wetlabs C-Star transmissometer), light intensity (PAR; Biospherical Instruments QCP2300) and surface light intensity (sPAR; Biospherical Instruments QCP2200). Quality control procedures were applied to the data. Data are available on the Polar Data Catalogue and at the Marine Environmental Data Service (MEDS) of Fisheries and Oceans Canada.

Benthic fauna were sampled at 78 stations between June and October from 2007 to 2011 onboard the Canadian research icebreaker CCGS Amundsen. Station depths ranged from 34 to 1024 m, all below the average ice scouring zone. All faunal samples were collected with an Agassiz trawl (effective opening of 1.5 m and a 40 mm net mesh size, with a 5 mm cod end liner) with average trawling time and speed of 5 min and 1.5 knots, respectively.

During the ArcticNet annual cruises of the research icebreaker CCGS Amundsen, characteristics of the near-surface atmosphere (basic meteorological elements, incident radiation, CO2 concentration) are monitored in conjunction with surface sea water properties (temperature, salinity, dissolved CO2 and O2) to observe the relationship between the surface micro-climate and the air-sea exchange, with particular interest in CO2. As part of this integrated dataset, the following radiation variables were recorded at 1 minute intervals (instrument used to collect each variable is in parentheses): -Incoming shortwave radiation (Eppley pyranometer, model PSP) -Incoming longwave radiation (Eppley pyrgeometer, model PIR) -Incoming photosynthetically active radiation (Kipp & Zonen, PAR-Lite) All instruments were mounted on a platform above the wheelhouse of the CCGS Amundsen

During the ArcticNet annual cruises of the research icebreaker CCGS Amundsen, characteristics of the near-surface atmosphere are monitored in conjunction with surface sea water properties to observe the relationship between the surface micro-climate and the air-sea exchange , with particular interest in CO2. Central to this integrated dataset is an eddy covariance system used to monitor fluxes of CO2, H2O, heat and momentum. The system continuously sampled the following variables at a rate of 10 Hz (instrument used to collect each variable is in parentheses, and approximate instrument height above surface is indicated): -3D wind velocity (Gill R3 and Gill Windmaster Pro ultra-sonic anemometer) - 15m -Sonic air temperature (Gill R3 and Gill Windmaster Pro ultra-sonic anemometer) - 15m -CO2 molar concentration (LI7500 open path gas analyzer) - 15m -H2O molar concentration (LI7500 open path gas analyzer) - 15m -CO2 mixing ratio (LI7000 integrated into a closed path system) - 15m -H2O mixing ratio (LI7000 integrated into a closed path system) - 15m -3D ship motion - angular rates and accelerations (MotionPak, Systron Donner) - 13m All instruments were mounted on a meteorological tower on the bow of the research icebreaker CCGS Amundsen.

The Canadian research icebreaker CCGS Amundsen is equipped with a Moving Vessel Profiler (copyright) (MVP), a multi-purpose instrument used to collect both shallow and deep water data sets, without the need to stop the vessel. Data on physical and chemical characteristics of the water column are collected during transects along which several consecutive casts of the MVP are conducted. The MVP was deployed during the Amundsen scientific expeditions, in the summer and fall of 2004 to 2018 with the exception of 2005 and 2006, where no data is available, and 2012 because the ship was undergoing maintenance. The components of the system varied slightly throughout the year but typically included a Micro CTD (Temperature, Conductivity and Pressure), a Micro DO2 (Dissolved Oxygen), a Micro SV (Sound velocity and Pressure) and an ECOFLO (Fluorescence) and a C-Star (Transmittance) probe. The MVP data were corrected and then controlled by comparing them to CTD-Rosette and thermosalinograph (TSG) data when available. Variables are provided for every decibar (dbar) between the maximum and minimum pressure recorded for each cast. Detailed metadata and reports are included to provide more information.

Samples collected by rosette or hand-deployed niskin, directly transferred into acid-washed and backed glass vials with teflon-lined silicone septa caps, and frozen at -20 or -80 C. Analyses conducted by high-temperature catalytic combustion and calibrated again standards provided by the University of Miami. In 2002, all samples were total organic carbon (TOC), and in 2003-04, all samples were dissolved organc carbon (DOC, filtered through combusted GFF), and TOC was also collected at full stations at in surface waters at the overwintering site.

The CTD data was obtained during the 2007-2008 scientific cruise #0707 within the framework of the Circumpolar Flaw Lead Study (CFL). This program included a year round sampling expedition to study the air-sea interactions occurring in the ice-free sections of the southern Beaufort Sea and Amundsen Gulf. The data were collected from November 10 to December 18, 2007, aboard the CCGS Amundsen. There were 105 casts, associated to 16 oceanographic stations, in the Beaufort Sea area. The following parameters were measured: temperature, conductivity and pressure (with a Sea-Bird SBE-9plus), dissolved oxygen (Sea-Bird SBE-43), pH (Sea-Bird SBE-18-I), fluorescence (Seapoint chlorophyll fluorometer), nitrate concentration (Satlantic MBARI-ISUS 5T), transmittance (Wetlabs C-Star transmissometer), light intensity (PAR; Biospherical Instruments QCP2300) and surface light intensity (sPAR; Biospherical Instruments QCP2200). Quality control procedures were applied to the data. Data are available on the Polar Data Catalogue and at the Marine Environmental Data Service (MEDS) of Fisheries and Oceans Canada.

Ringed seals have been reported to enter and use extensively the moon pool on multiple occasions during the CASES project. A net was designed to attempt to capture ringed seals from the moon pool onboard the CCGS Amundsen during a three week period of leg 6a. Captured seals were to be restrained, measured and a satellite transmitter (SPLASH PTT/TDR - Wildlife Computer) attached on their back before release. While one ringed seal did use the moon pool to rest during the three week period, we were not able to physically capture and tag any seals during the trip. We ruled out the net as designed in the first place as a good seal catching device in the moon pool, and created a new design that should be more functional. Considering seals' behaviour (once seals have found the moon pool, they keep using it) and how the moon pool is used onboard the ship, we discovered it was not necessary to deploy the net overnight if no seals have been spotted in the moon pool the day before. We are confident though that a future attempt to catch seals onboard the CCGS Amundsen will have more chances to be successful.