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Published April 28, 2022 | Accepted Version + Published + Supplemental Material
Journal Article Open

Bi‐Directional Energy Cascades in the Pacific Ocean From Equator to Subarctic Gyre

Abstract

Ocean circulation receives its energy input at basin scales while dissipates at microscopic mixing scale. How this energy is transferred across different lengthscales is of paramount importance for understanding the ocean circulation equilibration and variability. Advancement in high-resolution numerical simulations in recent years has significantly improved our understanding of kinetic energy (KE) cascades from basin to kilometer scales, although observational evidence to verify the simulated processes remains limited. Using repeat ship-board velocity measurements along 165°E across the equatorial, subtropical and subarctic Pacific Ocean, we show that the length scale separating the inverse and forward cascades, L_S, falls in the 8 ∼ 300 km range and it does not scale straightforwardly with the baroclinic deformation radius. Balanced and unbalanced oceanic motions co-exist in this range but contribute oppositely to the directional energy cascades. L_S is observed to depend on the relative strengths of these motions, as well as by their interaction.

Additional Information

© 2022. American Geophysical Union. Issue Online: 22 April 2022; Version of Record online: 22 April 2022; Accepted manuscript online: 18 April 2022; Manuscript accepted: 14 April 2022; Manuscript revised: 25 March 2022; Manuscript received: 01 January 2022. We are grateful to the past and present captains and crews of R/V Ryofu Maru and Keifu Maru, and staff of the Marine Division, JMA, for their long-term observational efforts. We also thank Rob Scott and an anonymous reviewer for their constructive comments that have helped to improve an early version of the manuscript. B. Qiu. and S. Chen acknowledge support from NASA OSTST mission (NNX17AH33G and 80NSSC21K1186). P. Klein acknowledges support of CNRS (France), LabexMer (ANR-10-LABX-19-01) as well as of the NASA-CNES SWOT mission. The authors declare no conflicts of interest relevant to this study. Data Availability Statement: The eddy kinetic energy data from global surface drifter program is available at https://www.aoml.noaa.gov/phod/gdp/mean_velocity.php. Japan meterological Agency maintains a website http://www.data.jma.go.jp/gmd/kaiyou/db/vessel_obs/data-report/html/ship/ship_e.php that includes the repeat shipboard Acoustic Doppler Current Profiler data along 165°E.

Attached Files

Published - 2022GL097713.pdf

Accepted Version - 2022GL097713-acc.pdf

Supplemental Material - 2022gl097713-sup-0001-supporting_information_si-s01.pdf

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Additional details

Created:
October 9, 2023
Modified:
October 24, 2023