Oceanographic observations (CTD and CDOM fluorescence) in the eastern Canadian Arctic Archipelago, northern Baffin Bay and Nares Strait in August-September 2024

Data are Conductivity-Temperature-Depth (CTD) and Colored Dissolved Organic Matter (CDOM) fluorescence profiles collected in August-September 2024 from the Canadian Coast Guard icebreakers Des Groseilliers and Amundsen in the eastern Canadian Arctic Archipelago in Nansen Sound, Eureka Sound, Norwegian Bay, Jones Sound, and Nares Strait and the northern Baffin Bay. Data file is in ASCII format.

The CTD observations from CCGS Des Groseilliers were carried out with a Sea-Bird Scientific SBE-19plus CTD that was accurate to ±0.005°C and ±0.0005 S m–1. The CTD observations aboard CCGS Amundsen were taken using a Sea-Bird 9plus CTD that was accurate to ±0.001°C and ± 0.0003 S m–1. CTDs were calibrated prior to the expeditions. We used practical salinity calculated directly from the conductivity and temperature of seawater as defined by Practical Salinity Scale 1978 (Lewis, 1980). All CTD casts were taken through the full water column (CCGS Amundsen) or to a maximum depth of 520 m (CCGS Des Groseilliers). All data was 1-meter binned.

The CTDs aboard CCGSs Des Groseilliers and Amundsen were outfitted with a Wet Labs ECO fluorometer for measuring CDOM fluorescence for EX/EM = 370/460 nm. The CDOM sensor sensitivity is 0.09 parts per billion (ppb). The CDOM sensor aboard CCGS Des Groseilliers was calibrated prior to the expedition. However, the resulting measurements were not post-calibrated against discrete samples. The CDOM sensor aboard CCGS Amundsen was not calibrated prior to the expedition resulting in data offset relative to that of CCGS Des Groseilliers. For overlapping, the CDOM profiles taken from CCGS Amundsen were adjusted by 1.77 mg m–3 assuming that for depths >500 m, the CDOM values at the mouths of Nansen Sound are consistent with that at the mouth of Nares Strait. CDOM profiles were averaged with a 7-meter moving window.

Our data shows that CDOM fluorescence assessed by optical sensors is a powerful tool for tracing water mass origins and circulation patterns. CDOM fluorescence can act as a tracer of Pacific water revealing how Pacific water transfers within the Canada Basin, flows through the Canadian Arctic Archipelago and Nares Strait and interacts with water of the West Greenland current in the northern Baffin Bay.

This data set supplements paper "Using Colored Dissolved Organic Matter (CDOM) fluorescence to trace the Pacific-derived water in the Eastern Canadian Arctic" by Igor A. Dmitrenko, Colin A. Stedmon, David G. Babb, Bert Rudels, Sergei A. Kirillov, Jens Ehn, Tonya Burgers, and Dorthe Dahl-Jensen accepted for publication in Scientific Reports, https://doi.org/10.1038/s41598-026-38848-2