Wind Variability at Synoptic-to-Planetary Frequency Enhances Front Asymmetry of Mesoscale Eddy.
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| Title: | Wind Variability at Synoptic-to-Planetary Frequency Enhances Front Asymmetry of Mesoscale Eddy. |
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| Authors: | Wu, Boyan1,2 (AUTHOR), Jing, Zhiyou1 (AUTHOR) jingzhiyou@scsio.ac.cn |
| Source: | Journal of Physical Oceanography. Jun2026, Vol. 56 Issue 6, p1-17. 17p. |
| Subjects: | Mesoscale eddies, Ocean dynamics |
| Abstract: | Oceanic fronts at mesoscale eddy peripheries are critical for generating submesoscale processes that regulate upper-ocean transport and mixing. Previous studies have shown that large-scale wind forcing can induce asymmetry in frontal sharpness around mesoscale eddies, with sharpened (weakened) fronts on the down-front (up-front) wind side. However, the response of these fronts and associated submesoscale processes to wind forcings at different oscillating frequencies remains poorly understood. Based on high-resolution idealized simulations of anticyclonic mesoscale eddy under various wind forcings, this study reveals that the modulation of frontal sharpness and asymmetry around anticyclonic mesoscale eddy is most significant when the wind oscillation period matches the eddy's rotational period. Analysis of Lagrangian particle tracking reveals that particles accumulate a net positive Ekman buoyancy flux (EBF) by experiencing an enhanced positive flux on the down-front wind side and a suppressed negative flux on the up-front wind side, which tends to strengthen the frontal asymmetry. Additionally, the submesoscale fronts sharpen significantly on the down-front wind side when wind stress relaxes. This frontal sharpening rate is driven by horizontal convergent flows, confirming the key role of submesoscale frontogenesis. Diagnosis of the horizontal divergence equation further reveals that local vorticity acceleration and nonlinear horizontal advection terms are primarily responsible in driving convergent flows and submesoscale frontogenesis. Given that 90% of mesoscale eddies exhibit rotational periods of 10 to 70 days, aligning with the dominant timescales of atmospheric variability, the mechanisms described above likely have significant influences on submesoscale frontal sharpness and asymmetry around mesoscale eddies across the global ocean. [ABSTRACT FROM AUTHOR] |
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| Database: | Engineering Source |
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| Abstract: | Oceanic fronts at mesoscale eddy peripheries are critical for generating submesoscale processes that regulate upper-ocean transport and mixing. Previous studies have shown that large-scale wind forcing can induce asymmetry in frontal sharpness around mesoscale eddies, with sharpened (weakened) fronts on the down-front (up-front) wind side. However, the response of these fronts and associated submesoscale processes to wind forcings at different oscillating frequencies remains poorly understood. Based on high-resolution idealized simulations of anticyclonic mesoscale eddy under various wind forcings, this study reveals that the modulation of frontal sharpness and asymmetry around anticyclonic mesoscale eddy is most significant when the wind oscillation period matches the eddy's rotational period. Analysis of Lagrangian particle tracking reveals that particles accumulate a net positive Ekman buoyancy flux (EBF) by experiencing an enhanced positive flux on the down-front wind side and a suppressed negative flux on the up-front wind side, which tends to strengthen the frontal asymmetry. Additionally, the submesoscale fronts sharpen significantly on the down-front wind side when wind stress relaxes. This frontal sharpening rate is driven by horizontal convergent flows, confirming the key role of submesoscale frontogenesis. Diagnosis of the horizontal divergence equation further reveals that local vorticity acceleration and nonlinear horizontal advection terms are primarily responsible in driving convergent flows and submesoscale frontogenesis. Given that 90% of mesoscale eddies exhibit rotational periods of 10 to 70 days, aligning with the dominant timescales of atmospheric variability, the mechanisms described above likely have significant influences on submesoscale frontal sharpness and asymmetry around mesoscale eddies across the global ocean. [ABSTRACT FROM AUTHOR] |
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| ISSN: | 00223670 |
| DOI: | 10.1175/JPO-D-25-0203.1 |
