Wind‐driven exchanges between two basins: Some topographic and latitudinal effects

Yang, Jiayan; Lin, Xiaopei; Wu, Dexing

doi:10.1002/jgrc.20333

Cited by 11 publications

(13 citation statements)

References 25 publications

(48 reference statements)

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“…This discrepancy may result from the neglect of nonlinearity associated with the eddy shedding at the southern and northern tips of Madagascar as well as the frictional effects. Both the nonlinear and friction effects in the 1.5-layer model or in the real ocean would dissipate some of the vorticity input from the wind stress curl, leading to a smaller T 0 value than the island rule would predict (Yang et al 2013). Overall, the timedependent Godfrey's island rule is able to dynamically explain the mean position and seasonal variation of the SBL.…”

Section: A Time-dependent Island Rule Modelmentioning

confidence: 79%

Seasonal Variation of the South Equatorial Current Bifurcation off Madagascar

Chen

Qiu

et al. 2014

Journal of Physical Oceanography

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In this paper, seasonal variation of the South Equatorial Current (SEC) bifurcation off the Madagascar coast in the upper south Indian Ocean (SIO) is investigated based on a new climatology derived from the World Ocean Database and 19-year satellite altimeter observations. The mean bifurcation integrated over the upper thermocline is around 188S and reaches the southernmost position in June/July and the northernmost position in November/December, with a north-south amplitude of about 18. It is demonstrated that the linear, reduced gravity, long Rossby model, which works well for the North Equatorial Current (NEC) bifurcation in the North Pacific, is insufficient to reproduce the seasonal cycle and the mean position of the SEC bifurcation off the Madagascar coast. This suggests the importance of Madagascar in regulating the SEC bifurcation. Application of Godfrey's island rule reveals that compared to the zero Sverdrup transport latitude, the mean SEC bifurcation is shifted poleward by over 0.88 because of the meridional transport of about 5 Sverdrups (Sv; 1 Sv [ 10 6 m 3 s 21 ) between Madagascar and Australia. A time-dependent linear model that extends the Godfrey's island rule is adopted to examine the seasonal variation of the SEC bifurcation. This time-dependent island rule model simulates the seasonal SEC bifurcation well both in terms of its mean position and peak seasons. It provides a dynamic framework to clarify the baroclinic adjustment processes involved in the presence of an island.

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Section: A Time-dependent Island Rule Modelmentioning

confidence: 79%

Seasonal Variation of the South Equatorial Current Bifurcation off Madagascar

Chen

Qiu

et al. 2014

Journal of Physical Oceanography

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“…It differs from skin friction because it is generated by the normal stress (mostly pressure) acting on the bed. Iino et al () and Yang et al () have shown that form drag can be more important than skin drag. Form drag can be expressed as

D_{form} = w \cdot \int_{x_{u}}^{x_{d}} P_{bot} \frac{dζ}{d x'} d x',

where P bot is the bottom pressure anomaly and

\frac{dζ}{d x^{'}}

is the topography slope over the bank.…”

Section: Topographic Drag At the Tg Straitmentioning

confidence: 99%

“…There are many theoretical studies that investigate the principal mechanism responsible for driving the annual mean EJS throughflow (Minato & Kimura, ; Nof, ; Nof, ; Ohshima, ; Toba et al, ; Tsujino et al, ; Yang et al, ). Most studies have shown that the volume transport through straits is related to the sea level difference across the three major straits (Ohshima, ; Toba et al, ; Tsujino et al, ) and that the large‐scale wind field of the North Pacific is the primary forcing agent, based on a mechanism analogous to the island rule (Godfrey, ).…”

Section: Introductionmentioning

confidence: 99%

“…Another aspect of a shallow strait is to induce form drag. Based on idealized bathymetry, Yang et al () suggest that shallow straits can significantly alter the dynamics behind the island rule because it blocks the geostrophic contours and restricts the exchange between two basins. Iino et al () show that the form drag caused by bottom topography is one of the main factors affecting the flow at the TG Strait based on a two‐dimensional model with detailed topography and a one‐dimension channel model with simple step/sill topography.…”

Section: Introductionmentioning

confidence: 99%

“…Even though past theoretical studies suggest bottom friction and form drag at the straits as the controlling factors for determining the magnitude of the transport through the straits, the dynamics have not been vigorously examined based on a configuration that considers three straits, stratification, and detailed topography simultaneously. The dynamics at the three straits are interconnected but most of the previous studies have been conducted only with a simplified model domain based on two straits (Seung, ; Yang et al, ) or only a single strait (Iino et al, ). Observation shows that stratification exists in the channels.…”

Section: Introductionmentioning

confidence: 99%

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The Role of Topographically Induced Form Drag on the Channel Flows Through the East/Japan Sea

2018

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The dynamics responsible for the East/Japan Sea throughflow are examined using the Finite Volume Coastal Ocean Model. Existing ocean data assimilation models (Δx~10 km) present overestimates of the volume transport through the Tsugaru Strait, and the outflow partitioning between the Tsugaru and Soya/La Perouse Straits also differs depending on the models. We find that this overestimate occurs when the form drag that is induced by detailed bottom topographic features in the Tsugaru Strait is not adequately resolved. A range of experiments with different horizontal resolutions in the Korea/Tsushima, Tsugaru, and Soya/La Perouse Straits were conducted to examine how detailed bottom topographic features in these three straits may affect the throughflow. We find that the volume transport is highly sensitive to the spatial resolution at the Tsugaru Strait but not at the Korea/Tsushima and Soya/La Perouse Straits. The high-resolution experiment showed a decreased outflow through the Tsugaru Strait and a reduction in the model bias. The outflow through the Soya/La Perouse Strait increased, while the inflow through the Korea/Tsushima Strait remained relatively unchanged. Additional experiments with modified topography further indicated that the abrupt change of the topography located at the upstream side of the Tsugaru Strait plays an important role in the outflow partitioning of the East/Japan Sea throughflow.

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On the dynamics of the seasonal variation in the South China Sea throughflow transport

Yang

Lin

2013

JGR Oceans

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[1] The Luzon Strait transport (LST) of water mass from the Pacific Ocean to the South China Sea (SCS) varies significantly with seasons. The mechanisms for this large variability are still not well understood. The steady-state island rule, which is derived from a steadystate model, is not applicable to seasonal time scale variations in a large basin like the Pacific Ocean. In this paper, we will use a theoretical model that is based on the circulation integral around the Philippines. The model relates the LST variability to changes in the boundary currents along the east coast of the Philippines, including the North Equatorial Current (NEC) Bifurcation Latitude (NECBL), the transports of Kuroshio and Mindanao Currents (KC and MC), and to the local wind-stress forcing. Our result shows that a northward shift of the NECBL, a weakening of the KC or a strengthening of the MC would enhance the LST into the SCS. This relationship between the LST and the NEC-KC-MC is consistent with observations. The analytical result is tested by a set of idealized numerical simulations.

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Wind‐driven exchanges between two basins: Some topographic and latitudinal effects

Cited by 11 publications

References 25 publications

Seasonal Variation of the South Equatorial Current Bifurcation off Madagascar

Seasonal Variation of the South Equatorial Current Bifurcation off Madagascar

The Role of Topographically Induced Form Drag on the Channel Flows Through the East/Japan Sea

On the dynamics of the seasonal variation in the South China Sea throughflow transport

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