Evolution of the eddy field in the Arctic Ocean's Canada Basin, 2005–2015

Abstract

The eddy field across the Arctic Ocean's Canada Basin is analyzed using Ice‐Tethered Profiler (ITP) and moored measurements of temperature, salinity, and velocity spanning 2005 to 2015. ITPs encountered 243 eddies, 98% of which were anticyclones, with approximately 70% of these having anomalously cold cores. The spatially and temporally varying eddy field is analyzed accounting for sampling biases in the unevenly distributed ITP data and caveats in detection methods. The highest concentration of eddies was found in the western and southern portions of the basin, close to topographic margins and boundaries of the Beaufort Gyre. The number of lower halocline eddies approximately doubled from 2005–2012 to 2013–2014. The increased eddy density suggests more active baroclinic instability of the Beaufort Gyre that releases available potential energy to balance the wind energy input; this may stabilize the Gyre spin‐up and associated freshwater increase.

Arctic Ocean surface geostrophic circulation 2003–2014

“…It has been known for some time that eddies are prevalent in the western Arctic Ocean, and that they make up a significant portion of the oceanic kinetic energy budget in this region (Manley and Hunkins, 1985). We find high EKE along the topographic margins of the Beaufort Gyre extending along the Northwind Ridge and Chukchi Ridge formations, consistent with the findings of Zhao et al (2016). Note that the satellite-derived EKE can only resolve ocean variability larger than the O(10 km) baroclinic eddies reported by Manley and Hunkins (1985) owing to the surface sampling and smoothing applied to the data (see discussion in Sect.…”

“…It is important to note that the satellite data will only resolve larger-scale ocean variability (greater than ∼ 50 km), not the O(10 km) baroclinic eddies reported by Manley and Hunkins (1985) that are observed in the hydrographic data by, for example, Zhao et al (2016). Despite this, the satellitederived EKE fields presented here are consistent with the theoretical model of Manucharyan and Spall (2016) that resulted in ocean variability of 100 km in scale.…”

“…The seasonal EKE climatologies presented here (Fig. 7) offer a complementary view to the hydrographic data presented by Zhao et al (2016), who do not resolve seasonal variability but reported enhanced eddy activity in the western Beaufort Sea after 2012. It is also possible that the northwest drift of the BG centroid (Fig.…”

“…It is also possible that the northwest drift of the BG centroid (Fig. 5) is also implicated in the enhanced eddy activity observed by Zhao et al (2016), as a larger portion of the gyre circulation intercepts the Northwind Ridge and Chukchi Plateau.…”

“…EKE has been estimated using satellite altimeters over the global ocean (Wunsch and Stammer, 1998) and in the Nordic Seas (Bulczak et al, 2015), and here we extend estimates of EKE into the central Arctic basins. There has been much recent interest in the role of eddies in the Arctic Ocean, particularly regarding their dissipative role in Beaufort Gyre dynamics (Timmermans et al, 2008;Cole et al, 2014;Manucharyan and Spall, 2016;Zhao et al, 2016), and here we provide a view of eddy activity that is complementary to detailed in situ observations using profilers and modelling studies.…”