The Canadian research icebreaker CCGS Amundsen is equipped with multi-plankton sampler system called Hydrobios. The MultiNet Type Maxi, part of the system, is used for vertical collections. An integrated CTD unit is also integrated to the system and allows recording of the sampled water characteristics. This dataset is composed of CTD profiles and specific data for the volume of water going through the nets during their operation. The Hydrobios was deployed during the Amundsen scientific expeditions in the summer and fall between 2003 and 2019 with the exception of 2004, 2005, 2009, 2011 and 2012, where no data is available. The integrated CTD sensors are from the Hydrobios company itself. The Hydrobios-CTD data were corrected and controlled by comparing them to CTD-Rosette data when available. Outliers and suspicious measurements were removed from the dataset. Variables are provided for every 2 decibars (dbar) between the maximum and minimum pressure recorded for each cast. Research programs participating in the Amundsen expeditions between 2003 and 2016 include CASES, ArcticNet, CFL, Geotraces, Malina, IOL and BP, BREA, Weston, Netcare, JAMSTEC, Statoil, iBO, GreenEdge, BAYSYS and DFO programs. In-situ data belong to and are under the responsibility of the leading Nets scientists while physical and chemical data from the sensors are part of the Amundsen core data collection.

The datasets present new data from microscopic counts and selected nutrient and physical data assembled from the following missions. Aboard the CCGS Louis St-Laurent: IPY Canada's Three Oceans 2007. Aboard the CCGS Amundsen: International Polar Year (IPY) Circumpolar Flaw Lead Study 2008; ArcticNet 2008. Temporal coverage is July-September. Cell density of the three sub-clades MAST-1A, MAST-1B and MAST-1C was measured by cell-counts using fluorescent in situ hybridization with taxa-specific probe. Biomass of phototrophic organisms, of different size classes, was obtained by counts of DAPI-stained cells under epifluorescence microscopy. Samples for total chlorophyll a (chl a) were filtered onto GF/F filters, extracted in either ethanol or acetone and analysed by spectrofluorometry. Chl a was also measured for the < 3 µm size fraction, and chl a in the < 3 µm size fraction was calculate by simple substraction. CCGS Amundsen data: Temperature, salinity, transmissivity, oxygen, and photosynthetically active radiation were provided by Dr. Y. Gratton (Institut National de la Recherche Scientifique, Québec). Nitrate and Phosphate concentrations were provided by Dr. J.-É. Tremblay (Université Laval, Québec). CCGS Louis St-Laurent data were supplied by Drs. E.C. Carmack and J. Nelson (Institute of Ocean Sciences, Sidney, B.C.). Distance to ice edge was obtained from the Canadian Ice Services (http://ice-glaces.ec.gc.ca).

The datasets present new data from microscopic counts and selected nutrient and physical data assembled from the following cruises. Aboard the CCGS Amundsen: ArcticNet Expeditions 2006, 2008, 2009, 2010; International Polar Year (IPY) Circumpolar Flaw Lead Study 2008 and MALINA Project 2009 (French IPY project headed by Dr. M. Babin). Aboard the CCGS Louis St-Laurent: IPY Canada's Three Oceans 2007. Temporal coverage is Feb.-Nov., but varies by year, with the greatest sampling effort in July-Oct. Cryothecomonas abundance was measured by cell-counts using fluorescent in situ hybridization with a taxon-specific probe. Biomass of phototrophic and heterotrophic organisms, of different size classes, was obtained by counts of DAPI-stained cells under epifluorescence microscopy. Samples for total chlorophyll a (chl a) were filtered onto GF/F filters, extracted in either ethanol or acetone and analysed by spectrofluorometry. Chl a was also measured for the < 3 µm size fraction. CCGS Amundsen data: Temperature, salinity, oxygen, and photosynthetically active radiation were provided by Dr. Y. Gratton (Institut National de la Recherche Scientifique, Québec). Nitrate and Phosphate concentrations were provided by Dr. J.-É. Tremblay (Université Laval, Québec). CCGS Louis St-Laurent data were supplied by Drs. EC Carmack and John Nelson (Institute of Ocean Sciences, Sidney, B.C.). Distance to ice edge was obtained from the Canadian Ice Services (http://ice-glaces.ec.gc.ca).

CTD data are obtained during the annual CCGS Amundsen scientific expedition. A large number of CTD rosette casts are performed every year. The rosette has twelve sampling water bottles and several instruments attached to its frame to collect water samples and records physical and chemical data (temperature, conductivity, pressure, fluorescence, light transmission, nitrate, photosynthesis) with sensors. The water samples are distributed to the scientific teams for in-situ analysis. In-situ data belong to and are under the responsibility of the leading scientists while physical and chemical data from the sensors are part of the Amundsen core data collection. Data typically measured each year and provided in this archive are as follows: 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; LI-COR Biosciences) and surface light intensity (sPAR; LI-COR Biosciences). Quality control procedures are applied to the data which are available under these formats: .int (one cast by file), .odv, .kml, .btl and .odf (on demand).

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.