How big are ocean currents? That question has been posed by generations of oceanographers, with partial answers available through measurements from ships, satellites, and numerical simulations. However, the answers were generally limited by methods used to decompose the kinetic energy of ocean currents according to their characteristic length scales. Namely, technical limitations of traditional Fourier spectral methods mean they are unable to capture strong currents near the coasts or currents with scales larger than roughly 1000km.
Research published in Nature Communications made use of coarse graining methods to study energy spectra of ocean currents, with these methods having none of the limitations of Fourier analysis. As a result, the researchers quantifiied the kinetic energy spectra for ocean currents across length scales from 10km to 10000km, and for all regions of the World Ocean. The research supports the well known property of the ocean mesoscale (100s km) as containing the bulk of the integrated ocean kinetic energy. Additionally, the research identified energy scales contained in ocean gyres and the Antarctic Circumpolar Current (ACC). The ACC has its energy peak at scales around 8000km, with this peak the largest spectral peak across all scales. A blog post on this research can be found here.
This research was led by University of Rochester scientists Ben Storer and Hussein Aluie (sabbatical AOS visitor in 2019), in collaboration with GFDL scientist and AOS faculty Stephen Griffies, former AOS postdoc Hemant Khatri (now at University of Liverpool), and University of Rome physicist Michele Buzzicotti.