Revealing the kinematic link between Arctic Ocean eddies and sea ice: inferring eddy characteristics from Lagrangian observations of ice motion

Small-to-moderate-scale ocean eddies (1–100 km) play a critical role in the freshwater budget and heat transport of the Beaufort Gyre (BG), a large circulation system in the Arctic Ocean. Quantifying the properties of eddies, however, poses significant challenges due to sparse in-situ measurements and the limited resolution of satellite altimetry. As an alternative approach, we use observations of sea ice pieces as tracers to characterize upper-ocean eddies within this scale in the BG. Here, we outline our methodology to infer BG eddy characteristics leveraging observations of sea ice (4–75 km). First, we use numerical simulations to explore a broad parameter space to establish the kinematic relationship between sea ice and the underlying eddies. Employing idealized vortex models, we obtain probability density functions for the rotation rate of sea ice in response to the vorticity of the eddies and derive analytical solutions for these parameters. We then expand our analysis to study geostrophic turbulence, providing a more realistic representation of BG eddies. In both cases, the PDFs peak at unity, reaching higher values as the sea ice size approximates the eddy length. Finally, we quantify the decadal and seasonal variability of BG eddy characteristics by applying the derived relations to actual sea ice observations. Our innovative approach opens new avenues to quantify Arctic Ocean eddy characteristics.