The CTD data was obtained during LEG 05 of the 2004 CASES scientific cruise #0402. This Leg was carried out from February 18th 2004 to March 30th 2004 aboard the CCGS Amundsen. There were 90 CTD casts in Leg 5. 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.