Water masses distribution in the Canadian Arctic Archipelago: Implementation of the Optimal MultiParameter analysis (OMP)

Abstract. The Canadian Arctic Archipelago (CAA) acts as a watershed discharge in the Arctic Ocean, as it is characterized by advection from the Pacific and Atlantic waters, ice melt, local river discharge and net precipitation. Its waters are characterized by the mixing of Pacific and Atlantic water origin, and the meltwater supply originating from the Devon Ice Cap Glaciers and marine-terminating rivers. The Special Report on the Ocean and Cryosphere in a Changing Climate published by the IPCC in 2021, showed how the runoff into the Arctic Ocean increased for Eurasian and North American rivers by 3.3 ± 1.6 % and 2.0 ± 1.8 % respectively (1976–2017), hence, monitoring the freshwater supply within the CAA is crucial in a warming scenario. This paper aims to describe the water mass structures within the CAA, by analyzing physical and chemical tracers collected in 2019 during the Northwest Passage expedition held in July and August onboard the Swedish icebreaker Oden. The uniqueness of this study is the wide dataset composed of physical and chemical parameters (https://doi.org/10.18739/A2W66995R). Here, we implemented the Optimal Multiparameter analysis for the detection of the source water fractions, such as, Atlantic Water (AW), Pacific Water (PW), Meteoric Water (MW), and Sea Ice Meltwater (SIM). For this analysis, we used a nutrient ratio tracer defined Arctic Nitrate-Phosphate tracer, together with the absolute salinity and δ18O from the water samples. Our analysis confirmed the intrusion of the PW from the west in the upper layers and of AW from the east in the deeper layers. We also discriminated the meltwaters between glacial and sea ice origin and showed their spatial distribution in the study area. This study provides unique set of data from this under observed region and can serve as baseline for further analysis and continued data collection.