Structure and Evolution of Temperature, Salinity, and Dissolved Oxygen in the Isolated Deep Waters of the Arctic's Canada Basin

Abstract The bottom waters of the Arctic Ocean's Canada Basin are vertically homogeneous and have C isolation age of 450 years. Understanding the evolution of this geothermally heated isolated bottom water and the overlying water layer can provide insights into Arctic circulation patterns, including interactions between shallow and deep waters, as well as past climate conditions that may have resulted in their isolation. Observations of deep and bottom‐water potential temperature , salinity , and dissolved oxygen from the Beaufort Gyre Observing System/Joint Ocean Ice Study (BGOS/JOIS) program are analyzed in context with property conservation equations, geothermal heating, vertical diffusion, and biological consumption. We find an approximately linear warming trend of the bottom waters over 2003–2024, updating a previous study ending in 2010. We additionally find trends of decreasing salinity and dissolved oxygen over the record. The structure of the bottom water varies spatially, with thinner, warmer, and fresher bottom waters with lower observed near the boundaries. Bottom‐water properties are fluxed vertically into an overlying potential temperature minimum layer, with enhanced vertical fluxes of heat, salt, and dissolved oxygen in turbulent regions near the basin boundaries, and lower, likely molecular vertical fluxes in the basin interior. Heat is fluxed laterally in the layer from the boundaries to the interior, resulting in approximately spatially uniform rates of warming of the layer. Over 2005–2024, decreasing bottom‐water suggests an important influence of organic matter remineralization. The findings in this study are consistent with continued isolation of bottom waters.