The Arctic Ocean is undergoing rapid change, with freshwater playing a central role in shaping stratification, vertical heat exchange, and sea-ice loss. Using long-term observations from the Nansen and Amundsen Basins Observational System (NABOS), we document a strong freshening event in the eastern Eurasian Basin between late 2015 and early 2017. During this period, salinity in the upper 175 m decreased by ∼ 0.5 psu, equivale...

The Siberian Arctic Ocean (SAO) is the largest integrator and redistributor of Siberian freshwater resources and acts to significantly influence the Arctic climate system. Moreover, the SAO is experiencing some of the most notable climate changes in the Arctic, and advection of anomalous Atlantic- (atlantification) and Pacific-origin (pacification) inflow waters and biota continue to play a major role in reshaping the SAO in r...

Located at the confluence of the Arctic and North Pacific and with Alaska at its heart, the Pacific Arctic Region (PAR) is a unique and interconnected regional climate system. Significant climatic changes in the PAR are described by a novel, mobile monthly Alaska Arctic Front (AAF) index, which is defined by sea level pressure differences between the migratory cores of the Beaufort High and Aleutian Low. Regional climate varia...

Glider observations conducted between 2016 and 2021 were combined with shipborne surveys from the 1950s through the 2010s to provide critically important information about changes in the Bothnian Sea. Particularly, we evaluated the rate of warming and freshening in several layers of the basin and showed that warming of 0.3°C/decade in the upper 25m was sufficient to explain ~40% of the oxygen depletion since the mid-1950s. Thi...

Continental slopes – steep regions between the shelf break and abyssal ocean – play key roles in the climatology and ecology of the Arctic Ocean. Here, through review and synthesis, we find that the narrow slope regions contribute to ecosystem functioning disproportionately to the size of the habitat area (∼6% of total Arctic Ocean area). Driven by inflows of sub-Arctic waters and steered by topography, boundary currents trans...

An important yet still not well documented aspect of recent changes in the Arctic Ocean is associated with the advection of anomalous sub-Arctic Atlantic- and Pacific-origin waters and biota into the polar basins, a process which we refer to as borealization. Using a 37-year archive of observations (1981–2017) we demonstrate dramatically contrasting regional responses to atlantification (that part of borealization related to p...

This study discusses along-slope volume, heat, and salt transports derived from observations collected in 2013–2015 using a cross-slope array of six moorings ranging from 250 to 3900 m in the eastern Eurasian Basin (EB) of the Arctic Ocean. These observations demonstrate that in the upper 780 m layer, the along-slope boundary current advected, on average, 5.1±0.1 Sv of water, predominantly in the eastward (shallow-to-right) di...

Heat fluxes steered by mesoscale eddies may be a significant, but still not quantified, source of heat to the surface mixed layer and sea ice cover in the Arctic Ocean, as well as a source of nutrients for enhancing seasonal productivity in the near-surface layers. Here we use 4 years (2007–2011) of velocity and hydrography records from a moored profiler over the Laptev Sea slope and 15 months (2008–2009) of acoustic Doppler c...