scholarly journals Role of Kuroshio Current in fish resource variability off southwest Japan

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Yushi Morioka ◽  
Sergey Varlamov ◽  
Yasumasa Miyazawa
Keyword(s):  
Rossby Waves ◽  
Kuroshio Current ◽  
Temperature Variability ◽  
Western Boundary ◽  
Ocean Temperature ◽  
Western Boundary Currents ◽  
Boundary Currents ◽  
Subsurface Ocean ◽  
Resource Variability ◽  
The Kuroshio

AbstractWestern boundary currents in the subtropics play a pivotal role in transporting warm water from the tropics that contribute to development of highly diverse marine ecosystem in the coastal regions. As one of the western boundary currents in the North Pacific, the Kuroshio Current (hereafter the Kuroshio) exerts great influences on biological resource variability off southwest Japan, but few studies have examined physical processes that attribute the coastal fish resource variability to the basin-scale Kuroshio variability. Using the high-quality fish catch data and high-resolution ocean reanalysis results, this study identifies statistical links of interannual fish resource variability off Sukumo Bay, Shikoku island of Japan, to subsurface ocean temperature variability in the Kuroshio. The subsurface ocean temperature variability off the south of Sukumo Bay exhibits vertically coherent structure with sea-surface height variability, which originates from the westward-propagating oceanic Rossby waves generated through surface wind anomalies in the Northwest Pacific. Although potential sources of the atmospheric variability remain unclarified, the remotely-induced oceanic Rossby waves contribute to fish resource variability off Sukumo Bay. These findings have potential applications to other coastal regions along the western boundary currents in the subtropics where the westward-propagating oceanic Rossby waves may contribute to coastal ocean temperature variability.

scholarly journals Shelf Currents within Different Oceans Under the Sun-Moon Gravitation

2019 ◽  
Vol 2 (1) ◽  
Keyword(s):  
Gulf Stream ◽  
Western Boundary ◽  
The Sun ◽  
Dynamical Equations ◽  
Western Boundary Currents ◽  
Boundary Currents ◽  
The Kuroshio

Here, I employed the shelf properties and sizes of different basins and introduced the Sun-Moon gravitation into the dynamical equations to dynamically explain the differences existing in the Gulf Stream and the Kuroshio systems. In addition to the classic western-boundary intensification of the western boundary currents that fails to explain why the differences in currents and ENSO significance exist among different oceans, shelf properties and sizes of different basins may produce another westernboundary intensification of the western boundary currents under the Sun-Moon gravitation.

Dynamics of Gap-leaping Western Boundary Currents with Throughflow Forcing

2021 ◽  
Author(s):  
Charles W. McMahon ◽  
Joseph J. Kuehl ◽  
Vitalii A. Sheremet
Keyword(s):  
Particle Tracking Velocimetry ◽  
Numerical Models ◽  
Western Boundary ◽  
Loop Current ◽  
Western Boundary Currents ◽  
Nonlinear Dynamical ◽  
Boundary Currents ◽  
Lab Experiments ◽  
Experimental Apparatus ◽  
The Kuroshio

AbstractThe dynamics of gap-leaping western boundary currents (e.g. the Kuroshio intrusion, the Loop Current) are explored through rotating table experiments and a numerical model designed to replicate the experimental apparatus. Simplified experimental and numerical models of gap-leaping systems are known to exhibit two dominant states (leaping or penetrating into the gap) as the inertia of the current competes with vorticity constraints (in this case the β-effect). These systems are also known to admit multiple states with hysteresis. To advance towards more realistic oceanographic scenarios, recent studies have explored the effects of islands, mesoscale eddies, and variable baroclinic deformation radii on the dynamical system. Here, the effect of throughflow forcing is considered, with particle tracking velocimetry (PTV) used in the lab experiments. Mean transport in or out of the gap is found to significantly shift the hysteresis range as well as change its width. Because of these transformations, changes in throughflow can induce transitions in the gap-leaping system when near a critical state (leaping-to-penetrating/ penetrating-to-leaping). Results from the study are interpreted within a nonlinear dynamical framework and various properties of the system are explored.

scholarly journals Subtropical Western Boundary Currents over Slopes Detaching from Coasts with Inshore Pool Regions: An Indication to the Kuroshio Nearshore Path

2012 ◽  
Vol 42 (2) ◽  
pp. 306-320 ◽  
Author(s):  
Hajime Nishigaki ◽  
Humio Mitsudera
Keyword(s):  
Bottom Layer ◽  
Volume Transport ◽  
Western Boundary ◽  
Bottom Slope ◽  
Boundary Current ◽  
Western Boundary Currents ◽  
Boundary Currents ◽  
Layer Velocity ◽  
The Kuroshio ◽  
Upper Boundary

Abstract The dynamics of subtropical western boundary currents over slopes detaching from coasts with inshore pool regions, where the water of the subtropical gyre does not enter and the velocity is small, are investigated. This study is intended to understand the dynamics of the nearshore path of the Kuroshio, which has a distinct boundary between the boundary current and the coastal water. Numerical experiments under idealized conditions are made. The results show flow patterns with pool regions similar to the Kuroshio under simple conditions. A deep countercurrent is present on the lower bottom slope, which represents observed deep currents. This is part of a deep cyclonic recirculation north of the jet, which extends to the lower bottom slope despite steep topography. This extension can be explained by the geostrophic contours. In this region, the upper boundary current feels the bottom slope and the westward intensification is blocked. In the other region, where the bottom-layer velocity is very small, the upper boundary current is free from the bottom slope and westward intensification occurs at the coast. The sensitivity to the volume transport of the boundary current is investigated by case studies. The pool regions are broken in cases with large volume transports. It is indicated that these unsteady inshore regions are produced by instability caused by an outcrop of the upper isopycnal, which is led by a large baroclinic volume transport.

scholarly journals Bjerknes-like Compensation in the Wintertime North Pacific

2015 ◽  
Vol 45 (5) ◽  
pp. 1339-1355 ◽  
Author(s):  
Stuart P. Bishop ◽  
Frank O. Bryan ◽  
R. Justin Small
Keyword(s):  
North Pacific ◽  
Kuroshio Extension ◽  
Western Boundary ◽  
Meridional Heat Transport ◽  
Western Boundary Currents ◽  
Boundary Currents ◽  
The North ◽  
The Kuroshio ◽  
The North Pacific ◽  
Kuroshio Extension Region

AbstractObservational and model evidence has been mounting that mesoscale eddies play an important role in air–sea interaction in the vicinity of western boundary currents and can affect the jet stream storm track. What is less clear is the interplay between oceanic and atmospheric meridional heat transport in the vicinity of western boundary currents. It is first shown that variability in the North Pacific, particularly in the Kuroshio Extension region, simulated by a high-resolution fully coupled version of the Community Earth System Model matches observations with similar mechanisms and phase relationships involved in the variability. The Pacific decadal oscillation (PDO) is correlated with sea surface height anomalies generated in the central Pacific that propagate west preceding Kuroshio Extension variability with a ~3–4-yr lag. It is then shown that there is a near compensation of O(0.1) PW (PW ≡ 1015 W) between wintertime atmospheric and oceanic meridional heat transport on decadal time scales in the North Pacific. This compensation has characteristics of Bjerknes compensation and is tied to the mesoscale eddy activity in the Kuroshio Extension region.

scholarly journals Radiating Instability of a Meridional Boundary Current

2008 ◽  
Vol 38 (10) ◽  
pp. 2294-2307 ◽  
Author(s):  
Hristina G. Hristova ◽  
Joseph Pedlosky ◽  
Michael A. Spall
Keyword(s):  
Western Boundary ◽  
Far Field ◽  
Boundary Current ◽  
Important Conclusion ◽  
Western Boundary Currents ◽  
Horizontal Structure ◽  
Boundary Currents ◽  
Zonal Jets ◽  
Eastern Boundary ◽  
Eastern Boundary Current

Abstract A linear stability analysis of a meridional boundary current on the beta plane is presented. The boundary current is idealized as a constant-speed meridional jet adjacent to a semi-infinite motionless far field. The far-field region can be situated either on the eastern or the western side of the jet, representing a western or an eastern boundary current, respectively. It is found that when unstable, the meridional boundary current generates temporally growing propagating waves that transport energy away from the locally unstable region toward the neutral far field. This is the so-called radiating instability and is found in both barotropic and two-layer baroclinic configurations. A second but important conclusion concerns the differences in the stability properties of eastern and western boundary currents. An eastern boundary current supports a greater number of radiating modes over a wider range of meridional wavenumbers. It generates waves with amplitude envelopes that decay slowly with distance from the current. The radiating waves tend to have an asymmetrical horizontal structure—they are much longer in the zonal direction than in the meridional, a consequence of which is that unstable eastern boundary currents, unlike western boundary currents, have the potential to act as a source of zonal jets for the interior of the ocean.

scholarly journals From the western boundary currents to the Pacific Equatorial Undercurrent: Modeled pathways and water mass evolutions

2011 ◽  
Vol 116 (C12) ◽  
Author(s):  
Mélanie Grenier ◽  
Sophie Cravatte ◽  
Bruno Blanke ◽  
Christophe Menkes ◽  
Ariane Koch-Larrouy ◽  
...  
Keyword(s):  
Water Mass ◽  
Western Boundary ◽  
Western Boundary Currents ◽  
Equatorial Undercurrent ◽  
Boundary Currents ◽  
The Pacific
Sign in / Sign up

Export Citation Format

Share Document