Apparent and inherent optical properties (AOPs and IOPs), stock measurement of seawater samples and particles and fauna distribution profiles with an Underwater Visio Profiler (UVP) were studied from July 8 to August 14 (Leg 1) mainly in the Labrador Sea, Baffin Bay and Lancaster Sound. Some measurements were made further North in the Nares Strait and the Kennedy Channel. As the UVP was integrated in the CTD/rosette system of the Amundsen, it was deployed through out the expedition until September 25th in Beaufort and Chuckchi Seas.
For the IOPs, 27 stations were sampled during Leg 1. IOPs profiles were measured using 2 optical packages, which include the following sensors: backscattering meters (from HobiLabs Hydroscat-6), fluorometers for colored dissolved organic matter absorption (CDOM) and chlorophyll. AOPs profiles were measured using a Compact-Optical Profiling System with 15 wavelengths (Biospherical). As for above-water radiometry, multispectral incident downwelling irradiance (Ed0+ at 15 wavelengths) was measured continuously from the top bridge using an irradiance meter (Biospherical) mounted on a 5-m telescoping mast. A sunphotometer was also used to derive the aerosol optical thickness and ozone concentration.
Seawater samples were collected at the surface and maximum chlorophyll fluorescence using the CTD-rosette system. Surface seawater was also collected from the barge and a bucket. Particulate absorption, CDOM, pigment concentrations (HPLC) and particulate organic carbon and nitrogen content samples were collected at 24, 21 and 19 stations respectively. All water samples were stored frozen. The analyses were achieved in laboratories at Laval University and the University of Québec at Rimouski. Particulate absorption was measured following Rottgers & Gehnke (2012) method using a Perkin-Elmer lambda 850 spectrophotometer, CDOM was measured using a variable pathlength spectrophotometer (Ultrapath), pigment were analyzed following Zapata et al. (2000) method and POC-PON were analyzed using a CHNS/O elementary analyzer.
The UVP enables identification and enumeration of zooplancton species and of sediment with size up to 200 µm. The open source software provided with the instrument is dedicated to the study of big particles (>100 µm) and study of zooplankton (mesozooplancton and micronecton). Pictures processing is achieved in a delayed mode. The UVP was deployed systematically at each CTD cast but for leg1a where it was under repair.
