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 WindMaster Pro ultra-sonic anemometer) - 15m -Sonic air temperature (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.

This dataset consists of vertical profiles of underwater downwelling irradiances at several UVR (305, 313, 320, 340 and 380nm) and PAR wavelengths, from June to August 2004. Vertical light profiles were performed using a PUV-511 underwater radiometer (Biospherical Instruments) that provides a measure of cosine-corrected downwelling irradiance in the UVR and PAR. Irradiances were corrected by the dark values and normalized to the ambient conditions at the beginning of the profile, using ambient values given by a GUV-510 surface radiometer (Biospherical Instruments) mounted on the top of the wheelhouse of the CCGS Amundsen.

The meteorological observatory Polarstern continuously acquires meteorological parameters during times of ship operation. Measurements are taken on various locations on the vessel, instrument heights above sea level are given below. All data is quality controlled. Measurements are checked daily on board by the operator and again prior to publication. Knowingly affected or erroneous data is removed.

The CTD data was obtained during LEG 04 of the 2004 CASES scientific cruise #0401. This Leg was carried out from January 7th 2004 to February 18th 2004 aboard the CCGS Amundsen. There were 119 CTD casts in Leg 4. All of these casts, associated to the overwintering oceanographic station, are located in Beaufort Sea research area. The following parameters were measured: temperature, conductivity and pressure (with a Sea-Bird 911 probe), oxygen (Sea-Bird 43), pH (Seabird 18), fluorescence (Seapoint fluorometer), nitrates (Satlantic MBARI ISUS), transmittance (Wetlabs C-Star transmissometer), PAR/Irradiance and SPAR/Irradiance (Biospherical Instruments QC2300). Data were quality controlled. Data are available on the Polar Data Catalogue and at the Marine Environmental Data Service (MEDS) of Fisheries and Ocean Canada.