Modulation of submesoscale motions due to tides and a shallow ridge along the Kuroshio

Masunaga, Eiji; Uchiyama, Yusuke; Zhang, Xu; Kimura, Waku; Kosako, Taichi

doi:10.1016/j.dsr.2022.103828

Cited by 6 publications

(4 citation statements)

References 55 publications

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“…• The western coast of Hokkaido; Four islands, including Rebun Island, Rishiri Island, Teuri Island, and Yagishiri Island, are located along the western coast of Hokkaido and contribute to the generation of submesoscale eddies via the process of topographic wake formation [11,60].…”

Section: • the Tsugaru Strait;mentioning

confidence: 99%

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The Characteristics of Submesoscale Eddies near the Coastal Regions of Eastern Japan: Insights from Sentinel-1 Imagery

Li,

He,

Wen

et al. 2024

JMSE

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A long-term time series of 319 Sentinel-1 SAR Imagery with Interferometric Wide Swath (IW) mode was used to study the characteristics of submesoscale eddies over Japanese coastal regions from 2015 to 2021, including spatiotemporal eddy properties and possible mechanisms of their formation. The results showed that around 98% of the 1499 eddies identified from the SAR snapshots were submesoscale eddies (horizontal scales of O1–20 km) with a ratio of around 78% cyclones to around 22% anticyclones. Around 8% of the submesoscale eddies were found in these SAR images in winter since the submesoscale current-induced signals are masked by the stronger wind speed, compared with other seasons. Typical features of submesoscale eddies are summarized, providing a preliminary qualitative analysis of potential generation mechanisms specific to the eddy characteristics in this region. This study suggests that Sentinel-1 images are capable of providing insights into the observed submesoscale eddies near the coastal regions of eastern Japan, thereby contributing to the improved understanding of the generation of submesoscale eddies.

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Section: • the Tsugaru Strait;mentioning

confidence: 99%

“…Japanese coastal regions, with their numerous capes, turns and islands, are enveloped in wind-driven circulation [9,10] and multiscale processes [11,12]. Submesoscale eddies near the coast have been studied in different regions based on multi-source data [13][14][15][16] and numerical simulation [17,18].…”

Section: Introductionmentioning

confidence: 99%

The Characteristics of Submesoscale Eddies near the Coastal Regions of Eastern Japan: Insights from Sentinel-1 Imagery

Li,

He,

Wen

et al. 2024

JMSE

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“…The 3-D Lagrangian transport of coral larvae was then numerically simulated using the precomputed 3-D flow field of the ROMS-L4 model output provided at 2 h intervals. An offline 3-D Lagrangian particle tracking model for ROMS was exploited (Carr et al, 2008), which has frequently been used in numerical studies on Lagrangian dispersal of virtual fluid parcels (e.g., Romero et al, 2013;Romero et al, 2016;Masunaga et al, 2022), larvae and eggs of marine fauna (Mitarai et al, 2009;Uchiyama et al, 2018b;Uchiyama et al, 2018c;Takeda et al, 2021), and even microplastic particles (Matsushita et al, 2022) with ample validations against in situ datasets of Lagrangian floats and drifters. Corals have various biological characteristics, such as larval behavior, larval precompetency period, and larval reproduction duration, depending on their species, habitat, and other conditions (Shlesinger and Loya, 1985;Baird et al, 2009).…”

Section: Offline Lagrangian Particle Tracking Model For Romsmentioning

confidence: 99%

Quantifying connectivity between mesophotic and shallow coral larvae in Okinawa Island, Japan: a quadruple nested high-resolution modeling study

2023

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Coral bleaching has recently been occurring extensively across the world’s oceans, primarily because of high water temperatures. Mesophotic corals that inhabit depths of approximately 30–150 m are expected to survive bleaching events and reseed shallow water corals afterward. In Okinawa, Japan, mesophotic coral ecosystems have been reported to serve as a refuge for preserving the genotypic diversity of bleaching-sensitive corals. The connectivity of larval populations among different habitats is a key element that determines the area to be conserved in desirable coral ecosystems. Because coral larvae are largely transported passively by ambient oceanic currents, particularly in the horizontal direction, numerical ocean circulation models greatly help to quantify connectivity with detailed spatiotemporal network structures. The present study aimed to quantify the short-distance connectivity of shallow and mesophotic coral larvae in reef areas on the northwest coast of Okinawa Island. To this end, a quadruple nested high-resolution synoptic ocean model at a lateral spatial grid resolution of 50 m was developed, which was capable of realizing detailed coastal currents influenced by complex nearshore topography, and coupled with an offline 3-D Lagrangian particle-tracking model. After validating the developed model, short-distance horizontal coral connectivity across reef areas on the northwest coast was successfully evaluated. The alongshore lateral connectivity had apparent asymmetry caused by depth-dependent horizontal currents, whereas the larvae spawned at shallow and mesophotic depths were reachable to each other. Such across-depth larval dispersal was attributable to the mixed-layer depth in the spawning period, viz., the boreal spring, which approximately coincides with the boundary between shallow and mesophotic coral, leading to the intensive vertical exchange of virtual larvae.

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“…The initial and side boundary conditions for the ROMS were provided by monthly climatology of the assimilative JCOPE2 oceanic reanalysis (Miyazawa et al, 2009). A one-way offline nesting technique was employed to convey the parent JCOPE2 to the child ROMS model with grid resolution refinement (e.g., Mason et al, 2010;Uchiyama et al, 2014;Kamidaira et al, 2017;Uchiyama et al, 2017;Kamidaira et al, 2018;Uchiyama et al, 2018a;Uchiyama et al, 2018b;Uchiyama et al, 2018c;Tada et al, 2018;Masunaga et al, 2018;Kamidaira et al, 2019;Masunaga et al, 2019;Zhang et al, 2019;Kurosawa et al, 2020;Kamidaira et al, 2021;Takeda et al, 2021;Uchiyama et al, 2022;Masunaga et al, 2022;Matsushita et al, 2022). Therefore, the horizontal grid spacing was successfully reduced from 1/12°(~10 km) of the JCOPE2 reanalysis to 3 km of the ROMS model, and vertically into stretched 32 s-layers (Shchepetkin and McWilliams, 2005) with grid height refinement near the surface and bottom to adequately resolve the boundary layers.…”

Section: Ocean Circulation Modelmentioning

confidence: 99%

Seasonal variability of upper ocean primary production along the Kuroshio off Japan: Roles of eddy-driven nutrient transport

et al. 2022

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We assessed spatial and seasonal variabilities of eddy-driven vertical nutrient fluxes, which are essential for maintaining primary production in the upper ocean. A climatological model based on a Regional Oceanic Modeling System (Regional Oceanic Modeling System) coupled with a Nutrient Phytoplankton Zooplankton and Detritus (NPZD) biogeochemical model at a submesoscale eddy-permitting resolution was used to investigate the mechanisms driving such variabilities around the Kuroshio, off the coast of Japan. The model realistically reproduced the spatial segmentations in primary production on both sides of the Kuroshio path with a higher chlorophyll-a concentration on the northern side than the southern side. In winter, downward eddy-induced nitrate flux is predominantly provoked in the upstream Kuroshio region (KR), while upward nitrate fluxes prevail in the downstream Kuroshio Extension (KE) region, due to both shear and baroclinic instabilities. Baroclinic instability plays a crucial role in inducing seasonal variability, leading to enhancement (reduction) of the eddy flux in winter (summer), particularly in regions away from the Kuroshio axis. Furthermore, we found that the influence of the Izu-Ogasawara Ridge, located in the KR, on regional dynamics and resultant spatial variability of the biogeochemical response are mostly confined in the KR. The Kuroshio is less turbulent in the upstream of the ridge, while it becomes unstable to shed mesoscale eddies in laterally wider and vertically deeper regions downstream. Consequently, although the near-surface nitrate concentration is lower downstream, the upward eddy-driven nitrate flux is more effective in maintaining active primary production due to the shear and baroclinic instabilities in winter.

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Modulation of submesoscale motions due to tides and a shallow ridge along the Kuroshio

Cited by 6 publications

References 55 publications

The Characteristics of Submesoscale Eddies near the Coastal Regions of Eastern Japan: Insights from Sentinel-1 Imagery

The Characteristics of Submesoscale Eddies near the Coastal Regions of Eastern Japan: Insights from Sentinel-1 Imagery

Quantifying connectivity between mesophotic and shallow coral larvae in Okinawa Island, Japan: a quadruple nested high-resolution modeling study

Seasonal variability of upper ocean primary production along the Kuroshio off Japan: Roles of eddy-driven nutrient transport

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