Ice-Tethered Profilers (ITP), deployed in the Arctic Ocean between 2004 and 2013, have provided detailed temperature and salinity measurements of an assortment of halocline eddies. A total of 127 mesoscale eddies have been detected, 95% of which were anticyclones, the majority of which had anomalously cold cores. These cold-core anticyclonic eddies were observed in the Beaufort Gyre region (Canadian water eddies) and the vicinity of the Transpolar Drift Stream (Eurasian water eddies). An Arctic-wide calculation of the first baroclinic Rossby deformation radius R d has been made using ITP data coupled with climatology; R d 13 km in the Canadian water and 8 km in the Eurasian water. The observed eddies are found to have scales comparable to R d . Halocline eddies are in cyclogeostrophic balance and can be described by a Rankine vortex with maximum azimuthal speeds between 0.05 and 0.4 m/s. The relationship between radius and thickness for the eddies is consistent with adjustment to the ambient stratification. Eddies may be divided into four groups, each characterized by distinct core depths and core temperature and salinity properties, suggesting multiple source regions and enabling speculation of varying formation mechanisms.

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.

Stirring along isopycnals is a significant factor in determining the distribution of tracers within the ocean. Salinity anomalies on density surfaces from Argo float profiles are used to investigate horizontal stirring and estimate eddy mixing lengths. Eddy mixing length and velocity fluctuations from the ECCO2 global state estimate are used to estimate horizontal diffusivity at a 300 km scale in the upper 2000 m with near‐global coverage. Diffusivity varies by over two orders of magnitude with latitude, longitude, and depth. In all basins, diffusivity is elevated in zonal bands corresponding to strong current regions, including western boundary current extension regions, the Antarctic Circumpolar Current, and equatorial current systems. The estimated mixing lengths and diffusivities provide an observationally based data set that can be used to test and constrain predictions and parameterizations of eddy stirring.

[1] The sampling characteristics of an underwater glider are addressed through comparison with contemporaneous measurements from a ship survey using a towed vehicle. The comparison uses the underwater glider Spray and the towed vehicle SeaSoar north of Hawaii along 158°W between 22.75°N and 34.5°N. A Spray dive from the surface to 1000 m and back took 5.6 h and covered 5.3 km, resulting in a horizontal speed of 0.26 m s −1 . SeaSoar undulated between the surface and 400 m, completing a cycle in 11 min while covering 2.6 km, for a speed of 3.9 m s −1 . Adjacent profiles of temperature and salinity are compared between the two platforms to prove that each is accurate. Spray and SeaSoar data are compared through sections, isopycnal spatial series, and wave number spectra. The relative slowness of the glider results in the projection of highfrequency oceanic variability, such as internal waves, onto spatial structure. The projection is caused by Doppler smearing because of finite speed and aliasing due to discrete sampling. The projected variability is apparent in properties measured on depth surfaces or in isopycnal depth. No projected variability is seen in observations of properties on constant density surfaces because internal waves are intrinsically filtered. Wave number spectra suggest that projected variability affects properties at constant depth at wavelengths shorter than 30 km. These results imply that isobaric quantities, like geostrophic shear, are valid at wavelengths longer than 30 km, while isopycnal quantities, like spice, may be analyzed for scales as small as a glider measures.

Ice-tethered profiler (ITP) measurements from the Arctic Ocean's Canada Basin indicate an ocean surface layer beneath sea ice with significant horizontal density structure on scales of hundreds of kilometers to the order 1 km submesoscale. The observed horizontal gradients in density are dynamically important in that they are associated with restratification of the surface ocean when dense water flows under light water. Such restratification is prevalent in wintertime and competes with convective mixing upon buoyancy forcing (e.g., ice growth and brine rejection) and shear-driven mixing when the ice moves relative to the ocean. Frontal structure and estimates of the balanced Richardson number point to the likelihood of dynamical restratification by isopycnal tilt and submesoscale baroclinic instability. Based on the evidence here, it is likely that submesoscale processes play an important role in setting surface-layer properties and lateral density variability in the Arctic Ocean.