AUTHOR=Chen Juntian , Zhu Xiao-Hua , Zheng Hua , Wang Min 

TITLE=Submesoscale dynamics accompanying the Kuroshio in the East China Sea

JOURNAL=Frontiers in Marine Science

VOLUME=Volume 9 - 2022

YEAR=2023

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.1124457

DOI=10.3389/fmars.2022.1124457

ISSN=2296-7745

ABSTRACT=Submesoscale processes in the ocean are vital for sustaining energy balance across scales. Taking advantage of the high resolution and wide coverage of numerical simulations, which are currently lacking for field observations, we investigated the basic patterns of submesoscale dynamics and mechanisms of corresponding variabilities along with the Kuroshio in the East China Sea. The large-scale western boundary jet serves as a remarkable submesoscale energy reservoir promoted by steep topographic features. In the found hotspots, that is, the continental slope and lee area of the Tokara Strait, long-lasting submesoscale footprints arose in the form of linear patterns of strongly skewed Rossby numbers with maximum values of ~O(1). Their origin may be derived from the high topographic-induced strain rate, which shows a consistent distribution and high correlation with the Rossby number. Corresponding to the characteristics of such active submescale processes, kinetic energy wavenumber spectra were obviously flatter than previous estimations of typical two-dimensional geostrophic turbulence and were not temporally fixed under combined works of multiple factors. The annual cycle of stratification induced seasonality by affecting mixed-layer instabilities, which control the kinetic and potential energy conversion rates. The tidal periods may because that the tides can generate inertia-gravity waves, which are partly overlapped in submesoscale ranges. Various other intermediate periods of variabilities were probably related to the eddy-caused Kuroshio path meander, which implied a closely coupled dynamical system across scales. Uncertainties come from ascertainment of the specific contribution ratios of each part, to be studied in the future.