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.

This study is based on sampling conducted partially within the framework of the (1) Arctic Biological Station program-Biological Oceanography Section (ABS-BOS) from 1973 to 1975, (2) CCGS Sir Wilfrid Laurier program and CASES from 2002 to 2004, (3) IPY-CFL from 2007 to 2008, (4) through research collaborations among the CCGS Amundsen program, ArcticNet, BP Exploration Operating Company Limited, ExxonMobil and Imperial Oil from 2009 to 2011, and (5) BREA in 2012. Macrobenthos communities were sampled at 235 stations from 1973 to 2012 between April and November through different scientific programs and onboard different research vessels. Faunal samples were collected mostly with a USNEL box corer (0.25 m2), except from 1973 to 2002 where different grab models were used. Due to shared sediment requirements, on average 0.12 ± 0.05 m2 of sediment were sieved from each box core or grab sample. All box core and grab catches were washed under running seawater onboard over a 0.4 mm sieve during the CASES program and over a 0.5 mm sieve during all other programs, resulting in all macrobenthic invertebrates considered here being ≥ 0.5 mm size. Taxa were preserved in a 4 to 5 % seawater-formaldehyde solution buffered with sodium tetraethylborate for later identification in the lab and then transferred in 70 % ethanol for long-term storage.

The CTD data was obtained during the 2007-2008 scientific cruise #0708 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 December 22, 2007, to January 30, 2008, aboard the CCGS Amundsen. There were 158 CTD casts, associated to 10 ice-drift stations, located in the Amundsen Gulf 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.

The CTD data was obtained during the 2007-2008 scientific cruise #0802 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 March 15 to April 23, 2008, aboard the CCGS Amundsen. There were 132 CTD casts, associated to 10 ice-drift stations, located in the Amundsen Gulf 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.

Continuous measurements of emissivity at 89 and 37 GHz frequencies in vertical and horizontal polarizations at a fixed elevation angle of 55 degrees during transit and scanning elevation angles of 30-150 degrees at every station were acquired. The radiometers were installed at the 200 level on the CCGS Amundsen icebreaker on the port side. Generally the instruments acquired data at the fixed elevation angle during transit, and 3-5 scans were performed at every station along with auxiliary data collection (GPS data, geographic location of the station, photographs of the same field of view, air temperature, wind data, atmospheric conditions, surface characteristics, etc.). The acquired data are in binary format which is produced for every scan and fixed modes. The time in the data logger is generally set to UTC. An example filename would be 'RADDAT-2007-11-06-122647.DAT'.

The CTD data was obtained during the 2007-2008 scientific cruise #0801 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 February 2 to March 13, 2008, aboard the CCGS Amundsen. There were 139 CTD casts, associated to 10 ice-drift stations, located in the Amundsen Gulf 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.

During the 2007-2008 CFL IPY Project, the research icebreaker CCGS Amundsen overwintered in the South Beaufort Sea/Amundsen Gulf flaw lead system. The purpose of this experiment was to comprehensively study the flaw lead system through an entire annual cycle. As part of this project, 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, PARlite) -Incoming UV-A radiation (Kipp & Zonen, UVS-AB-T) - available after April 4, 2008 -Incoming UV-B radiation (Kipp & Zonen, UVS-AB-T) - available after April 4, 2008 All instruments were mounted on a platform on the wheelhouse of the CCGS Amundsen.

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.

The all-sky camera system consists of a Nikon D-90 camera, with a wide-angle fish-eye lens, a homemade enclosure with clear acrylic dome end-cap, and a small heater on a thermostat. The system is mounted on a small 'crows nest' above the wheelhouse on the CCGS Amundsen. Maintenance checks were performed daily.

Continuous air samples were collected on Legs 8 and 9 of the CCGS Amundsen cruise in 2008 using a high volume air sampler that drew air through a glass fibre filter followed by two polyurethane foam plugs. Water samples were collected by filter water through a glass fibre filter followed by a solid phase absorbent. Samples were extracted back at the laboratory followed by analysis using a gas chromatograph-mass spectrometer. Data generated included concentration of semi-volatile contaminants in air and water and chiral signature of chiral components.