Inferring ocean eddy kinetic energy and enstrophy spectra from Lagrangian observations of ice motion in the Beaufort Gyre*

Oceanic eddies within the meso and submesoscale range play an important role in transporting heat and nutrients in the Beaufort Gyre (BG), a large-scale circulation system in the Arctic Ocean. Ocean kinetic energy and enstrophy spectra are critical to understanding ocean energy transport across different scales. Quantifying these dynamics, however, poses significant challenges due to sparse in-situ measurements. In the present study, we propose an approach to estimate enstrophy and kinetic energy spectra using sea ice rotation rates derived from satellite observations and quantify these spectra in the BG over the period spanning 2003-2020. Adopting a coarse-graining approach, we use ice floes as a Lagrangian spatial filter to construct the cumulative enstrophy spectra, whose derivative yields the enstrophy spectra and the corresponding kinetic energy spectra. We first verify our approaches using a discrete element sea ice model, Subzero, and quasi-geostrophic ocean models. We leverage Lagragian sea ice measurements using our ice floe tracker algorithm to infer energy and enstrophy spectra for different sea ice concentrations. Our innovative approach demonstrates the significant potential of Lagrangian sea ice observations for quantifying Arctic Ocean eddy variability.